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Blueprint of Life
1. Evidence of evolution suggests that the mechanisms of inheritance,
accompanied by selection, allow change over many generations.
Evolution: A change in species over a long period of time.
Natural Selection: The change in an organism over a long period of time that gives it
an evolutionary advantage enabling it to be better adapted to their environment and
therefore produce more offspring passing on its favourable characteristics to next
generation.
1.1 Outline the impact of the evolution of plants and animals of:
Changes in physical conditions in the environment
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Temperature, water availability, pH, light, salt concentration.
Example: Water availability has shaped the evolution of Kangaroos. There are
different species for different areas of Australia. Kangaroos show how evolution
has changed the animal.
Approximately 25 million years ago, Australia was considerably wetter than
today with large areas of rainforest. During this time, kangaroos were small and
omnivorous, with unspecialised teeth, eating a variety of foods from the forest
floor. Food was nutritious and abundant; there was no need for specialised
grinding teeth.
As Australia became more arid and grass became the dominant vegetation in
some areas, environmental selective pressure resulted in larger kangaroos
favouring teeth suitable for grass. They developed teeth for grinding and a multi
chambered stomach well adapted for the digestion of vegetation.
Changes in chemical conditions in the environment

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Iron levels & salinity in soil allows evolution of different plant species. Range of
salt tolerant plants that have evolved to inhabit these areas.
Acidophiles have evolved to be able to survive or even thrive in acidic
environments such as sulfuric pools and geysers and areas polluted by acid mine
drainage.
The sheep blowfly, Lucilia cuprina, is a major problem to the Australian sheep
industry. It stresses, weakens and can be lethal to sheep when larvae, laid by
females, burrows into wounds and wet wool. Chemicals, like organophosphates,
have been used extensively to control the blowfly. However, genetic resistance
has occurred within the fly population that has made these chemicals
ineffective.. Continued use of the insecticide has resulted in the mutation of a
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modifier gene that increases and maintains the resistance. Thus, the insecticides
can never be effective again, regardless of the number of blowfly generations
that pass.
Competition for resources
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Occurs within & between species
Resources that they fight for can be food, shelter and mates.
Introduction of dingo to Australian mainland increased the competition for food
for the Tasmania tigers. Dingos were more efficient predators because of their
pack behavior, so that eventually the tiger became extinct to the mainland.
1.2 Describe using specific examples, how the theory of evolution is supported
by the following areas of study:
Paleontology, including fossils that have been considered as transitional forms
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First bird that can fly: Archaeopteryx
Transitional fossil links reptiles and birds they were considered the first
animals that had features that allow flight.
Had wings, reptilian teeth and a long jointed tail, also has feathers and
wishbone sternum used to attach flight muscles.
Transitional fossils show the transition between 2 species.
Provides evolutionary pathway from dinosaurs to birds.
Biogeography


Study of the distribution of organisms over the Earth. These distribution
patterns provide evidence that species have originated from common
ancestors and, when isolated, have become new species as they have
adapted and evolved to their environment.
flightless birds (all came from similar ancestor – origin)
Cassowary= Australia + New guinea
Emu= Australia
Kiwi= NZ
Rhea= Sth America
Ostrich= Africa
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
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Explains the unique flora and fauna of Australia. Glossopterous:
Gondwana’s changing land mass shows evolution of species due to
changing conditions such as H20 and temperature.
Comparative Embryology
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Similar embryo’s suggest a common ancestor
Embryo’s of different species are very similar in the early stages of development.
Mammalian embryo’s have gill slits, tails, spinal cords and primitive kidneys.
Vertebrate embryo’s have the same type of skin that later develop into fish
scales, bird feathers etc
Comparative Anatomy

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We all have pentadactyl limbs (5 limbs) These limbs are modified
adaptations to different environments and suggest that these animals are
descended from ancestors with 5 fingered limbs.
Anatomical structures on different organisms that have the same basic
plan but perform different functions are called homologous structures.
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Biochemistry
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All forms of life are made up of DNA & RNA
All organisms have a similar code
Human haemoglobin studies are used to find how long since a commong
ancestor
More similar amino acids means more closely related
Very limited difference in DNA 1% with us and chimpanzees.
1.3 Explain how Darwin/Wallace’s theory of evolution by natural selection and
isolation accounts for divergent evolution and convergent evolution.
Darwin + Wallace
-
Natural selection
Variation in the environment, some variations are passed on to offspring
through reproduction
If several groups of the same species become isolated from each other, the
environments in which the groups are isolated may result in the selection of
different characteristic. If the differences are great enough, the groups will not
be able to interbreed to produce fertile offspring. New species have developed
Convergent
Divergent

Organisms that evolve have
 Common ancestor diverge &
similar structures & morphology
evolve into different looking
in
response
to
similar
organisms
environmental cues even though
 Eventually populations are so
they are unrelated.
different they can’t interbreed.
All from different ancestors and we Common Ancestor and diverge out.
have converged to look similar
If 2 totally different organisms begin to
utilize the same resource or occupy
similar niches, it is likely over time that
the environment will select those
characteristics that enable them to
survive and the organisms will develop
similar structures and physiology.
Shark & Dolphin
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Darwin’s Finches. Common Ancestor
than diverge out to look different.
Over time the finches diversified to
different foods and habitats. This gave
an advantage of avoiding direct
competition.
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Convergent
Divergent
The streamline
shape common
to seals,
penguins and fish.
Adaptive Radiation: Divergent evolution. Process by which organisms with common
ancestry become increasing different as they compete in different ways or inhabit
different habitats.
Convergent Evolution: evolving to be similar
Divergent Evolution: evolving to be different.
1A: Plan, choose equipment or resources and perform a first hand investigation to
model natural selection.
Model: demonstrate a scientific theory.
Theory: An explanation of a principle.
Aim: To model natural selection.
Materials:
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4 large sheets of coloured paper; yellow, red, orange & blue
20 Coloured toothpicks, 5 of each colour.
Stopwatch
Independent Variable: The colour of the paper used. Yellow, red, orange & blue
Dependent Variable: The number of sticks picked up.
Method:
1. Place 5 of each colour of toothpick onto
2. The colour of the board must match one of the colours of the coloured card
being used.
3. Capture ‘prey’ by quickly picking up coloured card squares in a given period
4. Count how many were picked up in the given time period, tabulate results and
repeat experiment.
Results:
20 of each sticks to begin with.
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Colour of Toothpick
Purple
Orange
Yellow
Blue
Green
Red
Number Picked Up
10
4
10
11
11
4
Conclusion:
I was able to model natural selection as the most sticks that were picked up in
environments where the sticks that did not camouflage into its surrounding habitat
showing the process of natural selection.
Discussion:
1. Discuss the links between your experiment and Darwin’s theory of natural
selection.
Darwin’s theory states that organisms will change over time and those that are better
suited to its environment have an advantage and are able to produce offspring that
have that characteristic and hence more likely to survive.
2. Identify the limitations of your model. Could the design have been further
improved?
We only tested one thing camouflage; could have used various utensils to test for
adaptations such as beak sizes. The limitations of the model are that it was only testing
one adaptations and that it didn’t imitate animal characteristics very well.
3. How did you/could you reduce the errors associated with measurement,
controlling variables and sampling?
We only had 1 dependent variable and that it was controlled. Also repeated it; each
piece of paper had the same amount of sticks.
1B. Analyse information from secondary sources to prepare a case study to show how
an environmental change can lead to changes in a species.
Peppered Moth: Separate peppered moth populations are usually either pale or dark
in colour. In unpolluted forests, pale moths are well camouflaged on the pale, lichencovered tree trunks. Dark moths stand out, therefore the birds eat them; white
population survives and therefore dominate the population. In polluted forests near
industrial cities tree trunks are blackened, the dark moths have advantage in colour.
Therefore dark moths have had higher survival rate in the polluted environment and so
now have become dominant.
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1. Name: Antibiotic Resistance: Staphylococcus aureus “Staph
Became resistant to pencillin, then became resistant to oxacillin and methicillin
2. Describe the change within the species: Became resistant to penicillin, as when
anti- biotics were first used they killed the bacteria that had low resistance and,
bacteria that had stronger resistance remained, they reproduced and only bacteria with
the stronger resistance was left; meaning it was more difficult to treat.
3. Illustration:
4. Describe the change in environment that occurred:
Natural selection and the use of anti biotics to kill bacteria. Bacteria that was resistance
was re producing, which there was more resistant bacteria in the environment.
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5. Identify whether the environmental change was a physical or chemical change.
The change was a chemical change. Species have chemical resistance to antibiotics.
Microevolution : evolutionary change within a species or small group of organisms,
esp. over a short period.
Macroevolution: major evolutionary change. The term applies mainly to the evolution
of whole taxonomic groups over long periods of time.
1C: Observe and analyse and compare the structure of a range of vertebrates
forelimbs.
Human, Dolphin, Bat, Frog, Lizard, Dog; all have
proportionate length of these bones varies, along with the
wide-ranging purposes: for swimming, flying and
walking. This pattern of similarity suggests common
ancestry and differences suggest evolution has occurred.
All have pentadactyl limb. (Humerus, Ulna & Radius,
Carpals, Metacarpals, Phalanges)
Vertebrate
Human
Humerus
Ulna, Radius
Provides site for
muscle
attachment
Dolphin
Bat
Ulna greatly
reduced and
attached to radius
strong allow
support for wings
Carpals
Phalanges
8
14 (each hand)
5
6
22
3 jointed
Efficient support
of body weight
Wrist highly
flexible allowing
the wing to be
folded down like
umbrella
Frog
Lizard
5
Dog
4
Efficient support
of body weight
confers strength
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1E Historical Development of Theories of Evolution, Assess social and Political
influences on these developments.
Date
1731-1802
1744-1829
Scientist
Erasmus Darwin
Jean Baptiste Lamarck
Contribution
Sexual Selection. Things could evolve from one to
another based on sex- traits passed down through sex.
Thought that if parents had sex for 3 mins blue eyes etc
All life came from a single source
First explanation for evolution: variation in species
developed due to use or disuse of body parts. These
changes passed on to offspring.
Theory incorrect.
Evolution through the environment. The environment
chooses your traits. Eg if you have a giraffe, the giraffe’s
neck will grow so it can eat the trees. Just growing
sporadically; growing to suit your environment. Not
through reproduction.
1809- 1882
Charles Darwin
His work challenged belief in creationism and
helped to make Darwin’s ideas more acceptable.
Published “origin of species by means of natural
selection”= came up with natural selection- an idea of
evolution
Later on showed how his theory could apply to humans
in the book Descent of Man .
How these developments were influenced by society and politics.

Predominant view in western cultures up until Darwin’s theory was
creationism. Diversity of living things created by God in six days- organisms
have not changed and are not related
- challenged comfortable idea that species were created independently
and did not change over time
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Despite scientific evidence; Darwin’s theory caused social political outrage.
1920s Protestant traditionalists campaigned against anti biblical ideas of
evolution
some states in USA; had laws banning teaching evolution in public schools
Today there is the theory of “intelligent design” as alternative to evolution.
Presented by William Paley used analogy of finding a watch on a beach and
making assumption that its existence is based on random events. Something
greater that made all our parts specifically.
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1D Analyse, using a name example, how advances in technology have changed scientific
thinking about evolutionary relationships.
Identify Technology/
Technologies
Describe advances in technology
Then
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Identify Scientific
Understanding
Now
Darwin (his book Descent of
Man)- belief humans from apes
Comparative anatomy,
embryology and behavioural to
support his idea of human
evolution
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DNA hybridsation
DNA sequencing
Amino Acid sequencing
(looking @ proteins)
Identify and describe advances in understanding
Then
Now
 He was the first to describe
evolution; even though he did it
superficially

Natural selection he proposed
Classify Species (from DNA
evidence) has changed because
of this. Not just based on
structural anatomy – Ernst
Haeckl (classified orangutans,
gorillas and chimpanzees in
one family and placed humans
in another). Biochemical
evidence disapproved this.
 Both DNA sequencing and
amino acids has changed our
understanding of human’s
relationship to chimpanzees,
gorillas and baboons- know
now that 1% of our DNA is
different to chimpanzees very
alike.
- orangutans diverged much
earlier
 DNA base sequencing

Change in direction or nature of scientific thinking
Technology
Understand how DNA works and sequencing it
Microscopes
Ability to sequence DNA
Ability to understand amino acids
Understand how chromosomes work
 We are more open minded
 We have gone to Darwin’s theory
 We understand that church and science doesn’t have to be separate
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Scientific Understanding
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1D Social and Political Influences of Evolution
Social and Political Events
The “enlightenment” or “Age of reason”
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Prestige of Science
Industrial evolution (1760-1840)
French Revolution (1789-
Philosophy of
Science
Thinking became
popular
Logic became known
Science became
something that could
be studied- that
things could be
figured out about the
universe.
Scientific Events
Prestige of science
increased. If you were
a scientist you were
thought to be elite- a
very high class. Well
respected.
Time of Lemark. Ideas of evolution
started to come in.
-
-
Microscope: science
became popular discovered
cells
Spontaneous generation
was disapproved
Science vs Religion
the two could not
coincide

Nature- new look on Science
Nature is of great
importance. This is
where all the
naturalists came
about.
Botanists came about: we started
to order species (etc classify
them)
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
1800-1900 Rise of Great Britain
1861-1865 American Civil War.
Science can be
studied at university
Biochemical Warfare: We used
science in a bad war: to kill. Agent
Orange, Radiation
Charles Darwin:
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2. Gregor Mendel's experiments helped advance our knowledge of the
inheritance of characteristics
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Mendel was a religious man; he was a monk of Austrian origin- also worked as
teacher and investigator.
Looked at how things were inherited.
Experimented by growing a variety of garden pea plants and recording the
resulting ratios of characteristic that appeared in the offspring.
He recognized a pattern in the inheritance of characteristics by offspring from
their parents and so he proposed a model of inheritance.
2.1 Outline the experiments carried out by Gregor Mendel
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Showed that inherited characteristics are passed down as discrete unit
from parents to their offspring.
This was shown through experiments with pea plants. Pea plants were used
because they can be easily cross-bred, have a short life cycle & both male &
female parts are prevent in their flowers.
Mendel created monohybrid crosses, the means it only has one characteristic ie
height (tall or short)
He located heredity which is the transfer of characteristics from one generation
to the next.
He had to control fertilization to make it valid
He said an organism characteristics are determined by ‘factors’ (we now call
them genes)
Mendel chose peas for his breeding experiments because:

The plants “bred true” for characteristics that he studied. He could establish true
breeding stock for contrasting characters such as tall stem/short stem or green
seeds/yellow seeds
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Garden peas can self fertilise. The parents could be artificially pollinated to
produce the first generation (F1). These offspring could be self fertilized to
produce the second generation.

Mendel’s explanations of his results are:
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Inheritance is not a blending of characteristics
Inheritance is controlled by a pair of particles in the cells which are he called
factors.
These two factors segregate from one another when sex cells are formed
Characteristics are either dominant or recessive.
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Trait
Seed Shape
Variations
Round or Wrinkled
Seed Colour
Yellow or Green
Seed Coat
Grey or White
Pod Shape
Normal or Constricted
Pod Colour
Green or Yellow
Flower & Pod Position
Axial (along stem) or Terminal (a top
of stem)
Stem Length
Long or Short
Eliminating Experiment Error:

To ensure pure breeding lines: over a period of two years, Mendel established
pure breeding lines. He ensure plants would self pollinate by using plants with
flower that had both female and male parts enclosed within the one flower.
These were kept in isolated greenhouses to avoid accidental cross pollination.

To ensure cross breeding: for each cross, Mendel manually transferred pollen
from the anthers of one pure breeding plant to the stigma of the contrasting
pure –breeding plant, but he first removed the anthers from the recipient plant
to ensure that it could not accidentally undergo self pollination. Using hundreds
of pea plants, Mendel manually transferred pollen.
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
Individuals have two factors for each characteristic and they may have two
factors the same (eg curly hair)
Mendel’s First Law Dominance
 The trait that is expressed in the hybrid individuals is dominant whereas the one
that is hidden is a recessive trait
Mendel’s First Law Segregation
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During gamete formation the pair of factors for trait segregate and each gamete
receives only once factor for the trait.
50% male or female.
Mendel’s Second Law Assortment
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When the inheritance of more than one trait is studied, the pairs of factors for
that trait separate independently of the other pairs of factors.
2.2 Describe the aspects of the experimental techniques used by Mendel that led to his
success
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Focused on specific characteristics rather than whole organisms and studied
how they were inherited from generation to generation
Lucky that characteristics observed were defined dominant/recessive
relationship
Reliable:
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Transfer of pollen (no cross breeding)
Studied a large number of characteristics (not just tall & short, 7 different)
Repeat
Analyzed his results mathematically to identify patterns and trends then applied
appropriate formulae to draw valid conclusions.
Valid:
 Controlled fertilization
 Could easily see characteristics
 Pure breeding plants (plants were not already cross bred)
Accurate:
 Could count the characteristics
 Reduced the possibility of experimental error- all experiments were conducted
in controlled environment (greenhouse).
 Those crosses that relied on self fertilization (to establish pure breeding lines)
conducted by keeping plants isolated from others – ensuring no cross
pollination.
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
Mendel removed stigma of some and anthers of others and then manually
transferred pollen from anthers of one plant to the stigma of another, preventing
errors arising from accidental self pollination.
2.3 Describe outcomes of monohybrid crosses involving simple dominance using
Mendel’s explanations.
y
First generation: dominant (F1)
3:1 ratio (F2) (3 dominant, 1 recessive).
Mendel’s factors (characters or traits from parents) pass as unmodified ‘units’ or
‘factors’ to successive generations according to set rations.
Examples:
1) Dad is double recessive for green eyes and mum is dominant for blue eyes but
carries recessive green eye.
G
Gg
Gg
g
g
g
gg
gg
2.4 Distinguish between homozygous and heterozygous genotypes in monohybrid
crosses.
Homozygous: Factors that are the same. Ie TT tt
Heterozygous: factors that are different. Ie Tt
Heterozygous condition the factor that is fully expressed is termed dominant (capital
letter) and the factor that has no noticeable effect is called recessive (lower case).
2.5 Distinguish between the terms allele and genes using examples.
A gene is a part of a chromosome. Genes determine the inherited characteristics of an
individual. Genes are passed from parents to offspring. Each inherited characteristics is
controlled by a least two genes.
Allele: a particular inherited characteristic. The different forms of a gene that occur on
the same place on homologous (ie matching) chromosomes. Ie gene for height as two
alleles T and t.


Occur in pairs in a diploid individual, but two or more alleles for each gene
may be present in a population
Segregate during gamete formation (meiosis)
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
Occur individually in each haploid gamete pair during fertilization, when the
diploid condition of an organism is restored during zygote formation
Zygote: a diploid cell resulting from the fusion of two haploid gametes; a fertilized
ovum.
Gene: is a section of DNA on a chromosome



It codes for proteins that express themselves as the phenotype of an organism
Specifies a particular characteristic
Has two alleles in an individual and two or more alternative alleles in a
population
2.6 Explain the relationship between dominant and recessive alleles and phenotype
using examples
Phenotype: is the outward appearance of an organism
Genotype: is the actual alleles that are present on the chromosomes of the organism.
A homozygous tall plant would have two identical alleles for height (TT) and would
appear tall (phenotype). This is represented by two dominant alleles.
A heterozygous tall plant would have the phenotype of a tall plant but would have non
identical alleles (Tt)
2.7 Outline the reasons why the importance of Mendel’s work was not recognized until
some time after it was published.

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
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Mendel’s work published in 1866; at the time it was thought inheritance
involved a blending of characteristics. Mendel showed that characteristics were
not blended.
No established reputation or recognition in scientific community.
He showed that inherited characteristics are determined by discrete units called
factors.
Importance of his work not recognized till 1900 because biologists in 1866
did not have the background to understand what Mendel had accomplished. nothing known about chromsomes and genes
Now have improvements in microscopes and staining techniques- making
it possible to examine the cell nucleus and chromosomes
It is the chromosomes in the nucleus that carry the “factors” as described by
Mendel. These factors we now call genes.
2A Construct pedigrees or family trees, trace the inheritance of selected characteristics
and discuss their current use
Refer to Sheet with Key
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2B Solve problems involving monohybrid crosses using Punnett squares or other
appropriate techniques
2C Process information from secondary sources to describe an example of
hybridization within a species and explain the purpose of this hybridisation
Hybridization: process of cross breeding different organisms. Hybridisation within a
species occurs between different identified strains or types
Corn: purpose of hybrid is to produce a plant that has a beneficial combination of
alleles than its true breeding parents. Hybrid corns grows more vigorously, resists
disease and insect pest, tolerates stress more effectively Better yield crops.
3 Chromosomal structures provides the key to inheritance
3.1 Outline the roles of Sutton and Boveri in identifying the importance of
chromosomes
Mendel did not know about genes and chromosomes; Sutton and Boveri noted the
similarity between the behavior of chromosomes and Mendel’s laws (1904).
Units of heredity on chromosomes were later termed genes (1909) and their
inheritance patterns are now used to explain the ratios derived in Mendels laws.
Sutton (1902-03)

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
Worked with grasshoppers
Mendel “factors” are carried on
chromosomes
Showed crossing over of
genetic materials during
meiosis
Showed genes are inherited
Boveri (1903)
 Worked with sea urchins
 Showed chromosomes are
transferred from one
generation to the next
 Sperm & egg contribute equal
number of chromosomal info.
 Connection between hereditary
and chromosomal
Sutton Showed:






Chromosomes carriers of hereditary units and the units are transmitted with the
chromosomes
Chromosomes occur as matching pairs (homologous pairs)
Result of meiosis: every gamete receives only one chromosome of each
chromosome pair
Chromosomes keep their individuality throughout cell division
Distribution of members of each homologous pair is independent of that of each
pair
Since hereditary factors are more numerous than chromosomes, each
chromosome has to carry many units.
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Chromosome Theory of Inheritance:
Confirmed by Morgan (1910-11): experimental evidence: sex linkage
Where in the cell are
hereditary factors
found?
What materials store
the hereditary
information?
Before Sutton & Boveri
Cytoplasm and Nucleus
After Sutton & Boveri
Nucleus only
Unsure- perhaps
proteins?
A full set of paired
chromosomes, where
many hereditary factors
are carried on each
chromosome
Random assortment,
during meiosis- units of
inheritance carried on
Chromosomes in
gametes
Chromosomes occur in
set numbers in every cell
in pairs and each pair of
chromosomes has the
same size and shape
How are inherited
factors passed on?
Gamest transport
“factors” but how what
these factors were was
unknown
Nature of
chromosomes
Chromosomes were
believed to disappear
and reappear and were
all believed to be the
same size and shape
3.2 Describe the chemical nature of chromosomes and genes
Chromosome:


60% proteins (histone), 40% DNA (chromosomes made up of more protein than
DNA)
Compact coils of – thread like molecules, called DNA (deoxyribonucleic acid)
organized around proteins called histone
Genes:




Section of DNA (thread holding them together is proteins)
Made up of a sequence of bases
Different genes are different lengths
Genes are a section of DNA that stores information as a cooled sequence & each
gene is located at a particular site or locus on a chromosome
Chromosomes
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DNA
Genes (smallest unit of hereditary info)
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3.3 Identify that DNA is a double – stranded molecule twisted into a helix with each
strand compromised of a sugar phosphate backbone and attached bases –
adenine (A), thymine (T), cytosine (C) and guanine (G)- connected to a
complementary strand by pairing the bases, A-T and G-C
DNA
 Double stranded
 Double helix shape
 Bases
A
T
G= C



Held together by hydrogen bonds. Double bond between A & T
and triple bond between G &C.
Backbone is sugar and phosphate, bases attach to the sugar
molecule. (think salt and pepper)
Hydrogen bonds between nitrogenous bases
Nitrogenous Bases
A= Adenine
T= Thymine
G- Guanine
C= Cytosine
Nucleotide

Made up of phosphate group, sugar, and a nitrogenous base attached to the
sugar
DNA molecule is long chain molecule consisting of two complementary strands. Each
strand is made up of a sequence of many nucleotides and the strands are held together by
weak hydrogen bonds in the centre. The two strands in the double helix model have an
‘antiparallel’ arrangement- that is they run in opposite directions.
Genetic Unit: 3 base code sequence
Each nitrogen base code carries a set of instructions for controlling the inheritance and
all the chemical processes that will occur in the cell
A gene controls the putting together of amino acids to make proteins
Amino Acids are the building blocks of proteins.
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3.4 Explain the relationship between the structure and behavior of chromosomes
during meiosis and the inheritance of genes.
Zygote:
What is the role of meiosis?
 Mechanism for halving the number of chromosomes when gametes are
produced.
 Also mixes the paternal and maternal chromosomes and these recombined
chromosomes are passed into gametes, increasing the genetic variation.
How is Meiosis achieved?



Crossing over of genetic material
Random segregation: randomly going over. Paternal and maternal chromosomes
assort independently from each other.
Different pairs of homologous chromosomes behave independently of each
other and each pair segregates randomly to the daughter cells
What is meant by diploid and haploid?



Diploid two sets of chromosomes; one paternal set and one maternal set
Haploid: single set of unpaired chromosomes (half)
Start has diploids then go into haploid.
What is random segregation?
 Separation of maternal and paternal chromosomes ensures chromosomes
number in the resulting gametes will be half that of original cell
What is independent assortment?

Manner in which chromosomes separate paternal and maternal chromosomes
sort themselves independently
Why does meiosis take place?



To create sex cells so there is genetic variation
To get from diploid to haploid cells
Reproduction
It is worse to breed with your cousin than brother or sister:
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3.5 Explain the role of gamete formation and sexual reproduction in variability of
offspring

Halving the chromosomes number (n) (diploid to haploid) and sexual
reproduction results in combining gametes results in combining gametes
(haploid to diploid) to produce a new diploid organism (2n). The
processes involved in forming this new organism result n variability of
the offspring.
Two different stages lead to variability
1. Ovum and Sperm joining together during fertilization is random process- new
combo genes. Genetic Variation
2. Random Segregation of Individual Chromosomes different combinations of
maternal and paternal chromosomes. Genetic Variation
3. Process of crossing over Chromosomes exchange parts of genetic info- segment.
Genetic Variation


Sexual Reproduction: female/male cells produces 4 sex cells (gametes)
from process of Meiosis
Each of these sex cells is haploid and has a random assortment of genes
from the parent. The genes are separated and the sex cells have a rand
assortment of dominant and recessive genes. More variability is
introduced depending on which sex cells are successful in fertilization.
The resulting embryo has a completely different set of genes from either
of the parents.
3.6 Describe the inheritance of sex linked genes, alleles that exhibit co- dominance
and explain why these do not produce simple Mendelian rations
Some crosses did not give the expected Mendelian ratios of offspring
Sex – linked inheritance produces variations to Mendel’s predicted outcomes.
Sex linked inheritance results from genes carried on either the male or female
chromosome
XX females
XY males
Co Dominance: occurs when effects of both alleles (gene pairs) appear together in the
heterozygous offspring
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3.7 Describe the work of Morgan that led to the understanding of sex linkage
Quick Summary: Refer to more detail sheets
Drosophila Melanogaster to answer questions about variations in inherited
characteristics. They studied crosses between red eyed and white eyed flies and found that
the offspring could not be explained using Mendel’s scheme. Morgan made hypothesis
which he tested with large numbers of crosses. His hypothesis was that the gene for white
eyed characteristics is part of the X chromosome- said that genes that are on the X
chromosome are sex linked.
3.8 Explain the relationship between homozygous and heterozygous genotypes and
the resulting phenotypes in examples of co- dominance
Homozygous: contains two of the same alleles for the same trait eg BB or bb
Heterozygous: contains a hybrid of alleles for the same trait Bb
Phenotypes: the expression of the alleles (the genotype)
Genotypes: the alleles present in an organism that determines the phenotype


When both alleles are expressed in the phenotype; the two alleles are said to be
co dominant. Both labeled with upper case letters. Eg human blood groups –
AB co dominant
Shorthorn cattle= have an allele for red and white hair- as neither is dominant
cattles with both alleles have a mixture of red and white hair. Ie RW (red and
white hair)
3.9 Outline the ways in which the environment may affect the expression of a gene
in an individual
Nature: genetically determined
Nurture: influence of the wider environment
The effect of a gene can be enhanced or masked by variation in the environment.
Effect Environment Has on Plant:


Acidity or alkalinity of soil influences colour of flowers
Hydrangeas growing in acidic soil develop blue flowers where as those
grown in alkaline soil develop pink flowers hence the environment
affecting the phenotype.
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Effect Environment has on an animal.

Lack of nutrient/presence of toxins (like cigarette smoke) can restrict growth =
effecting expression of genotype- even if tall genotype could be short because of
the environment
Factors in environment such as: availability of water, nutrients, sunlight, type of
soil, presence poisonous substances, competition
3A: Model meiosis and the processes of crossing over, segregation of chromosomes and
the production of haploid gametes
Using Lolly Snakes
3B: Solve problems involving co- dominance and sex linkage
Practice throughout Exam Prac:
3C: Perform FHI to demonstrate the effect of the environment on phenotype.
Aim: To investigate the effect nutrients have on the phenotype of Bean plants
Equipment:






Soil
Plastic cups x4 (2 with fertilsier, 2 without fertilizer)
Paper Towel
Fertiliser
Bean seeds
Measuring equipment
Risk Assessment:
 Inhale fertilizer, to reduce risk keep away from soil
Independent Variable: Fertiliser vs non fertilizer
Dependent Variable: Plant features: height, colour, leaves, produce
Control: A plant that with water and soil
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Method:
1.
2.
3.
4.
5.
6.
Place 20 grams of soil into 4 cups that contain holes to allow water to drain
Carefully place 2 bean seeds into each of the 4 cups.
Add fertilizer to two cups
Add 15mls of water to all four cups
Repeat experiment
Leave plants, in an area where they will obtain the same amount of sunlight and
allow plants to grow.
7. Record the plants features including height, colour, leaves and produce after two
weeks.
4 The Structure of DNA can be changed and such changes may be
reflected in the phenotype of the affected organism
4.1 Describe the process of DNA replication and explain its significance
Gene Expression
 Copy genes that are specific for proteins
 Making a protein that is specific for a particular trait
DNA Replication:
1. Single Strand
2. DNA unwinds
3. Nucleotides come in then 2 DNA strands
4.2 Outline using a simple model, the process by which DNA controls the
production of polypeptides.
 DNA controls the production of long chains of amino acids (polypeptides) which
make up proteins.
 20 different amino acids can form the polypeptide chain
 Order in which bases are arranged in the DNA molecule forms the genetic code
Steps in Protein Synthesis:
1. RNA polymerase (enzyme) binds to part of the DNA. DNA unzips, unspirals and
hydrogen bonds between two strands break
2. Transcription of the gene occurs controlled by the enzyme RNA polymerase.
RNA nucleotides are assembled forming complementary single stranded mRNA
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3.
4.
5.
6.
7.
8.
molecule. (DNA is transcribed into mRNA) – sequence the same but U has
replaced T. In the Nucleus
mRNA moves out of nucleus into cytoplasm encounters ribosomes
Translation: ribosomes move along mRNA molecule and attach tRNA molecules
by temporarily paring the bases of tRNA anticodons with their complementary
triplets of bases condons on mRNA
Amino acids linked together by an enzyme to form polypeptide chain
tRNAs move away from mRNA
Polypeptides further processed, folded into their correct shape forming protein
mRNA broken down into nucleotides – can be reused
Transcription and Translation:
1.RNA polymerase starts to read the DNA
2. MRNA is made
3. MRNA leaves the pore
4. Translation. Outside cell, ribosome reads
5.TRNA: brings amino acids and anticodon
6. TRNA: leaves and brings polypetides and then when longer enough folds up and
becomes a protein
Transcription: takes places in the nucleus; it writes out a copy of the DNA into
messenger RNA
Translation: Ribosomes reads mRNA sequence and translates it into amino acid
sequence of the protein. Happens inside cytoplasm.
Anticodon:
a sequence of three nucleotides forming a unit of genetic code in a transfer RNA
molecule, corresponding to a complementary codon in messenger RNA.
RNA: nucleotides coming in (sugar, phosphate, base): T is eliminated and U is brought
it (Uracil)
Ribosomes: read RNA and stick it to other proteins
Non coding strand (sense) strand: strand of DNA that contains genetic info for
protein
DNA is a code: tells your body what proteins to make
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4.5 Explain how mutations in DNA may lead to the generation of new alleles
Mutagen: natural or human made agent (physical or chemical) which can alter the
structure or sequence of DNA. Code is not read properly therefore not copied properly
Mutagens can be Carcinogens (cancer causing) or Teratogens (birth defect
causing)
Mutations can be inherited
Mutations can be acquired
- mistakes in when DNA is replicated
Environmental Factors Increase Rate of Mutation
-
X- Rays, atomic bomb, UV light (causes melanoma)
Hans Muller (Nobel Prize 1927): Showing genes have ability to mutate when exposed
to X-Rays. Similar to Beadle and Tatum
Atomic Bomb: Hiroshima and Nagasaki. 10 fold increase in cancer deaths, unless
mutagens can cause death but unless they affect the sex cells the effect is not
passed on to the next generation.
4.6 Explain how an understanding of the source of variation in organisms has provided
support for Darwin’s theory of evolution by natural selection.




Foundation pillars for the theory of evolution is the variation that occurs
among individual members of a species
Basis of this variation is the genetic makeup of the individuals in a
species, it is this selection acts upon.
Mutation of DNA provides a new source of variation supporting Darwin’s
theory of evolution
Mutations provide a mechanism to explain how heritable variation arises.
4C Construct a flow chart that shows that changes in DNA sequences can result in
changes in cell activity


If there is simple substitution for a single base pair on a strand of DNA such as
G-C replaced by A-T, then this results in a different amino acid codon forming a
different polypeptide
Deletion: if one base pair is lost from the sequence there will be a shift along the
DNA molecule producing different polypeptide
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4.7 Describe the concept of punctuated equilibrium in evolution and how it differs from
the gradual process proposed by Darwin.
Punctuated equilibrium: Evolution occurs in short bursts of rapid change, followed
by long periods of stability. Most species adapt until they reach a stable stage and are in
a state of equilibrium with their environment. Can last millions of years or can be
punctuated by rapid evolutionary change.
They suggest that if evolutionary change is gradual, fossilized remains would show
these ongoing changes.
However fossil records shows millions of years without any noticeable evolutionary
change to most species. Soft bodied organisms dominated the seas for hundreds of
millions of years, then in a period of a few million years they disappeared and
were replaced with organisms with shells and skeletons.
Punctuated equilibrium questions whether it occurs in short burst of rapid change or
gradually over a long period of time.
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4.E Describe and analyze the relative importance of the work of James Watson, Francis
Crick, Rosalind Franklin, Maurice Wilkins
James Watson
List their area of expertise






Watson American biologist: completed his PHD in genetics
Joined with crick who was also interested in DNA
Discovered that living cells is DNA, deoxyribonucleic acid, is a giant molecule in
the form of a double helix.
Their major discovery was made by piercing together the arrangements of
atoms,
The discovery of the structure of the DNA, unlocked a whole new understanding
of the ‘blueprint of life’- that every cell of every organism contains DNA,
Discovered that the molecular structure allowed DNA to unzip and make copies
of itself and the complementary base- pairing, held together by hydrogen
bonding.
Analyse and describe interaction with other scientists
Discuss the recognition that was given to them for their discoveries

Nobel Prize in Psychology or Medicine in 1962
Identify people that have influences their career.



Wilkins presented his findings on the X-ray crystallography of DNA at a
conference on molecular biology which is where James Watson met and inspired
his interest in DNA
After viewing Franklin’s photographs – Watson and Crick produced their first
model – however it was wrong.
Wilkins later showed them a high quality x-ray crystallography picture of DNA
that Franklin had recently produced – provided measurements and details to
which Watson paid close attention – When Crick saw the photograph he
recognized the double helical nature of the molecule.
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Francis Crick
List their area of expertise
Analyse and describe interaction with other scientists
Discuss the recognition that was given to them for their discoveries

Nobel Prize in Psychology or Medicine in 1962
Identify people that have influences their career.
Rosalind Franklin
List their area of expertise


Chemist who had advanced technical and analytical skills in X-ray
crystallography and diffraction.
Able to separate the two different ‘hydration forms’ of DNA, which allowed her
to produce clear, precise X-ray diffraction pictures from which accurate
measurements could be obtained.
Analyse and describe interaction with other scientists


Rosalind franklin thought she would be working independently on DNA,
following up Wilkins initial work, while he would work on proteins.
However when he returned from leave he took up his work on DNA and saw
himself as Franklin’s senior.
Discuss the recognition that was given to them for their discoveries


At the time being a female she was often excluded from casual scientific
discussions that took place in staff dining rooms.
She was not given any formal recognition as she already died, and the Nobel
prize cannot be already posthumously.
Identify people that have influences their career.


Wilkins provided Franklin with some of the best DNA samples in the
world at the time
The First model by Watson and Crick; was wrong and she turned down
the suggestion from Watson and Crick that she join them.
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Maurice Wilkins
List their area of expertise
New Zealand born physicist = expertise was producing crystalline organic
molecules for examination by X-ray crystallography
Analyse and describe interaction with other scientists

Discuss the recognition that was given to them for their discoveries

Nobel Prize in Psychology or Medicine in 1962
Identify people that have influences their career.
Analyse the importance that collaboration and communication (or lack of) had
on the discovery of DNA



It was very important as it allowed the progression of ideas and the further
development as well as a complete understanding of other people’s
thoughts/processes = greater mind power
X-ray crystallography can be used to determine the shape of a large molecule –
but it does not reveal the actual arrangement of atoms
Both processing information from other researchers, long discussions and many
hours spent manipulating models, Watson and Crick’s idea took shape and
seemed to work- the double helical structure…..
5.1 Identify how the following current reproductive technologies may alter the genetic
composition of a population: artificial insemination, artificial pollination, cloning
Selective Breeding:
Brief Description:

Form of artificial selection imposed by humans, when they conduct deliberate
crosses of living organisms to obtain a combination of desirable characteristics.
Contrasts to natural selection where environmental conditions determine which
individuals produce the most offspring.
Animal Example:
Male Friesian variety with (produces lots of milk), with a Jersey cow (produces
creamy milk)
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Offspring: some will produce large amounts of creamy milk.
These offspring then selected for further breeding
Note: Parent individuals have to be different varieties of same species so offspring
fertile
Plant Example:
Mendel and his pea experiments: removing the stamens of a flower and dusting polen
onto the stigma of the same flower or another flower
Advantages:

Increases production- large quantities of creamy milk
Disadvantages:
 Breeding of undesirable characteristics eg physical disadvantage is that these

hybrid cows have large udders that they can barely walk
Time consuming and costly. Transport of large animals over long distances,
waiting for them to mate- that is why artificial insemination is now used.
Artificial Insemination
Brief Description:


Involves taking sperm from a chosen male and artificially introducing it into
several selected females
Semen removed from male and the fluid is chilled and then frozen in liquid
nitrogen for long term storage and transported
Example: IVF: (in vitro fertilization) – fertilization happens outside the woman’s body,
fertilization of egg by sperm takes place in glass dish, fertilized egg is then implanted
into uterus where it develops
Advantages:
 Transporting frozen sperm overcomes the problem of transporting large


animals over large distances- cost effective, removes dangers to animals in
transit
Many females can be inseminated, with sperm of one male
Use in conservation, to increase numbers of endangered species
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Disadvantages:
 Many offspring from one father, leads to reduced genetic variability
 Increasing sterility; genes that would have been eliminated in natural
populations will be passed onto offspring and remain part of the population.
Artificial Pollination:
Brief Description:


Requires fertilization. Pollen from selected breed o plant with desirable traits is
artificially transferred to the female stigma. Creates new hybrid species and so
alters genetic population, new gene combinations are created and some genes
are now more common than before.
Used in agriculture to produce large numbers of organisms with desirable
characteristics: such as in Kiwi fruits- when shortage of bee hives
Advantage:
 greater quantities of fruit/agriculture
Disadvantage:

reduction in biodiversity- some genes are more common, effects survival of
plant and food cycle = more plants available that would not normal be available
Cloning
Brief Description:
Selective breeding relies on some extent “trial and error”- hoping that the desired
combination of favourable genes ends up in some individuals, which can then be
selected and interbred.
Cloning involves making an individual identical to the one that already exists. Used in
seedless grapes and bananas, therapeutic cloning in humans- for macular
degeneration
Genetic Engineering: modifying an organism – adding a desirable gene to the DNA of
an individual or removing and substitution a gene and then ensuring that, when it
reproduces, it passes this gene on with all of its other genes creating a transgenic
species
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Types of Cloning:
Reproductive Cloning: involves creating a genetically identical, fully developed
(whole) organism, using a cell from another mature organism. Reproductive technology
Therapeutic Cloning: Using cells from an individuals to produce a cloned early embryo
which is then used as a source of embryonic stem cells to replace degenerating adult
tissues or to repair damage.
Gene Cloning: Happens at Cellular level involves producing identical copies of a gene,
important step in process of genetic engineering
Advantages:

characteristics can be precisely controlled and organisms can be produced in
short periods of time (without testing needed in selective breeding)
Disadvantages:

if all species are identical, population is less likely to survive of sudden
environmental changes, vulnerable to foreign pathogens.
Describe how the each of the above techniques can alter the genetic composition of the
population
Artificial insemination alters the genetic composition as it reduces the genetic variability; as the sperm
of one man can used to produce many babies to many females, the sperm from one man is fertilized by
different embryos in a glass dish and is then inserted into the individual mothers . Artificial
pollination also reduces the biodiversity as plants with desirable characteristics are selected and
reproduce increasing the commonality of particular genes and reducing variability, by carefully
placing the pollen of a plant onto the stigma of another plant; selective breeding also acts in the same
way. Cloning also reduces the variability of genes to a greater extent as the species are identical by
copying exactly the genetic composition of another organism of a species.
Also consider:


Genes for infertility , which would not naturally have been passed on, are now
inherited by offspring. Breeding infertility into population, opposite to natural
selection, where frequency of genes that enhance fertility increase
Sperm Banks can alter gene composition of population, people choose traits that
are more desirable – elimination of certain genes means other important alleles
may be lost (eg disease resistance)
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5.2 Outline the processes used to produce transgenic species and include examples of
this process and reasons for its use.
Biotechnology: any technique that uses living organisms to make products. Modern
biotechnology involves manipulating DNA of living organisms, to artificially combine
specific qualities of different organisms.
Genetically Modify: add or remove genes.
Transgenic: Species that has been created by moving a gene from one species and it
becomes part of that organisms genome (DNA) and can be inherited by subsequent
generations. Involves inserting the gene into a ‘germ-line’ cell – a cell that will give rise
to new offspring. The gene should be inserted into fertilized egg cell that gives rise to an
organism.
Gene therapy: a healthy copy of a gene is inserted into defective tissue only. Therefore
it will not be passed on to the next generation. Gene therapy will be used as a new form
of medicine, to replace conventional treatments for diseases and the desirable gene will
be inserted into the non germ line tissue in a developed or mature plant or animal.
What are some applications of transgenic species
• Being produced for specific economic traits. Transgenic cattle were created to
produce milk containing particular human proteins, which may help in the
treatment of human emphysema.
• Other transgenic animals are produced as disease models (animals genetically
manipulated to exhibit disease symptoms so that effective treatment can be
studied). For example, Harvard scientists made a major scientific breakthrough
when they received a U.S. patent (the company DuPont holds exclusive rights to
its use) for a genetically engineered mouse, called OncoMouse® or the Harvard
mouse, carrying a gene that promotes the development of various human
cancers.22
Detailed Example:
Reason for the production of transgenic cotton:

Traditional pesticides used on cotton plants had to be made stronger and
applied more frequently to get rid of caterpillars- the caterpillars were building
up resistance to the pesticides
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


Bt cotton plants were genetically modified and contain a gene that codes for the
production of a protein that kills the caterpillar – the insertion of this gene
reduced the need for pesticide
The Gene is called Bt: as it was originally taken from the soil bacterium Baciullus
thuringiensis
This has also been beneficial as using a powerful broad spectrum sprays
Helicoverpa Zea moth from which the caterpillar comes from used to wipe out
beneficial bugs such as ladybirds and wasps
Process used to produce transgenic cotton
1. Cut normal cotton seedlings; they grow into calluses
2. Put in liquid medium given hormones to make them grow into embryos
3. Bt gene extracted from bacteria using restriction enzymes and placed into the
cotton – using a vector Agrobacterium which is able to inject genes into other
cells (cotton dipped in solution of the Bt gene and the vector)
4. Embryos germinated into small plants; which are then planted and grown in
greenhouses
Restriction enzymes recognize very specific DNA sequences and cut both strands of
DNA at those specific locations. Thus, when one knows the sequence of the
gene/genome in question, one is able to make targeted cuts to extract only specific
parts which are of interest.
Why have scientists developed four different insecticidal genes to use in cotton?

Bollgard II cotton contains two inserted genes and produces two lethal proteins
against the caterpillar. It is highly unlikely that the caterpillar will become
resistant to both genes. In addition, cotton farmers plant a refugee crop of pea
plants in fields nearby, so that moths with one recessive allele for resistance to
Bollgard II continue to interbreed with moths who feed on the ‘refuge crop’, to
reduce the chances of in-breeding caterpillars with double recessive alleles
which could confer resistance.
The project has been described as very controversial, with critics claiming that it
is doing more harm than good. Discuss this statement, identifying issues and
providing points for and against the use of this transgenic species.
Advantages:
Pest resistance Crop losses from insect pests can be staggering, resulting in devastating
financial loss for farmers and starvation in developing countries. Farmers typically use
many tons of chemical pesticides annually. Consumers do not wish to eat food that has
been treated with pesticides because of potential health hazards, and run-off of
agricultural wastes from excessive use of pesticides and fertilizers can poison the water
supply and cause harm to the environment. Growing GM foods such as B.t. corn can
help eliminate the application of chemical pesticides and reduce the cost of bringing a
crop to market4, 5.
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Negatives:
Unintended harm to other organisms Last year a laboratory study was published in
Nature21 showing that pollen from B.t. corn caused high mortality rates in monarch
butterfly caterpillars. Monarch caterpillars consume milkweed plants, not corn, but the
fear is that if pollen from B.t. corn is blown by the wind onto milkweed plants in
neighboring fields, the caterpillars could eat the pollen and perish.
Unknown effects on human health There is a growing concern that introducing foreign
genes into food plants may have an unexpected and negative impact on human health
Allergenicity Many children in the US and Europe have developed life-threatening
allergies to peanuts and other foods. There is a possibility that introducing a gene into a
plant may create a new allergen or cause an allergic reaction in susceptible individuals.
A proposal to incorporate a gene from Brazil nuts into soybeans was abandoned
because of the fear of causing unexpected allergic reactions31. Extensive testing of GM
foods may be required to avoid the possibility of harm to consumers with food
allergies. Labeling of GM foods and food products will acquire new importance, which I
shall discuss later.
Using steps outline the process used to create a transgenic species
Process of Gene Manipulation:
1. ‘Cut’: a gene for a favourable characteristic is removed from the cell of an
organism, using restriction enzymes
2. ‘Copy’: multiple copies are made (called gene cloning) – usually carried out in
bacteria
3. ‘Paste’: genes are inserted (injected) into an egg cell of another species and after
fertilization become part of the newly formed organism’s DNA.
4. The egg develops into a mature organism (a transgenic species) with the new
gene ‘switched on’ to function.
Gene Delivery Techniques:
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1. micro injection of DNA directly into the nucleus of a single cell- under opitical
microscope- introduce DNA into egg cells
2. Biolistics: methods of mechanically delivering DNA on microscope particles into
target tissues and cells by firing them from a gene- tiny gold particles used to
coat DNA which is then fired at target cells
3. Transduction by a viral vector: DNA may be carried by vectors such as an
adenovirus, liposomes or bacterial plasmids into cells. Can be injected into
bloodstream or by aerosol delivery (nasal spray).
Assessing whether the gene has been incorporated:

Gene for fluorescent protein from jellyfish is now used to determine whether an
individual has successfully incorporated a transgene. It is used as a marker and
attached to desired gene. If the individuals have been transformed, they will be
fluorescent under certain lighting conditions.
5.3 Discuss the potential impact of the use of reproduction technologies on the genetic
diversity of species using a named plant and animal example that have been genetically
altered.
Cloning:
Describe how cloning increases genetic diversity


Since a breeding cow has a limited life span, its genes could be stored under
laboratory conditions and used for cloning in the future- therefore improving
the genetic diversity of a breed by offering more options for future generations.
Also used to try and increase the numbers of endangered species and to
reintroduce genes from extinct animals such as the thylacine into their gene pool
Describe how cloning decreases genetic diversity


Organisms produced by reproductive cloning are derived from only one parent
and are genetically identical to the parent
Increases the frequency of particular genotypes therefore as a result of artificial
selection, natural gene combinations that are not selected will gradually
disappear
Note: Alleles which may be of benefit in the future (eg in resisting pathogens) may be
lost making it vulnerable
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Artificial Pollination:
Describe how artificial pollination increases genetic variability?



Increases due to hybrid species = new combinations of alleles are introduced
Eg wheat hybrids were created by crossing purple straw variety with Yandilla to
create new variety called Federation (hybridisation within a species results in
hybrids that are fertile as opposed to hybridisation across species where they are
infertile)
Greater genetic diversity within the gene pool equips a species for adaptations
and survival if there is a sudden environmental change such as an epidemic
disease of food shortage.
Describe how artificial pollination increase genetic variability?


Longer term continued breeding of same hybrid lines decreases genetic
diversity- the overuse of one breeding line, or ‘in breeding’ of hybrids from the
same parental lines, leads to a greater chance of the offspring inheriting two
copies of the same detrimental allele from their closely related parents.
Also less likely to survive sudden environmental change or pathogens
5.A Describe a methodology used in cloning
What the animation “What are clones?”
1. ‘What are clones?”

Clones are organisms that have identical genetic material. The sequence of their
bases in their DNA is exactly the same.
2. List some examples of cloning



Identical twins have exactly the same DNA
A plant cutting can also be used to generate a clone
1950s creating frogs from frog embryonic cells
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3. What is cell differentiation?


After a small number of cell divisions, embryonic cells star to change into the
different types of cells that an organisms needs, including cells that form muscle,
blood and liver.
Although these cells have the same genetic info, each cell can only access the
genes needed for its particular function
4. Why did scientists think it would impossible to clone an entire organism
after differentiation?

It was thought that once cells differentiated, they could not be used to generate
an entire organism. For instance, in a sheep, udder cells could generate other
udder cells but not an entire sheep
5. Outline the process of cloning dolly in a flow chart.
6. When was dolly born?
Dolly born July 5 1996.
7. The phenotype of the offspring is the same as the nucleus donor.
Scientists found she had the same DNA as the udder cells she came from (from nucleus
donor). Clone of the udder cells.
8. Who was Bonnie?

Dolly’s lamb produced the natural way
9. Where was the cloning of Dolly performed?
Roslin Institute
10. Where was the cloning of mice first performed?

Laboratory in Hawaii run by Dr Ryuzo Yanagimachi – successfully clone an
animal from an adult cell
11. Outline the process used to clone the mouse in the form of a flow chart
12. When was the cloning of mice performed?
October 3 1997 – host mouse gave birth to Cumulina
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5.B Analyse information from secondary sources to identify examples of the use of
transgenic species and use available evidence to debate the ethical issues arising from
the development and use of transgenic species.
Description of a transgenic species


Transgenic field peas that contain a gene from French beans that produce a
protein that causes pea eating insects to starve to death
Strawberries in Scandinavia have been transformed with a salmon gene that
allows them to grow in cold conditions
The positives and negatives effects transgenic species have on society
Positives:



Increased yield
Ability to implement transgenic species into countries where there is poor
nutritional value/ people are malnourished.
Grow in all conditions= such as the strawberries
Negatives:






Animals such as cows are being injected with hormone bST, to increase milk
production. The hormone is engineered using microbes; has health effects for
humans and increases the chance for mastitis (bacterial infection of nipples) in
cows– cows are given increased doses of anti biotics coutner this
Is it morally right? – eg cows that are unable to stand because they have such
large udders
Some are concerned that the eugenics movement will return. By selecting
characteristics that are desirable- form of selective breeding.
Will disrupt evolutionary relationships as it will disrupt the rate of gene transfer
between organisms and the way genes are transferred. – speed up rate of
genetic change
Genetically engineered organisms released into the environment may cause new
diseases or encourage the development of strains resistant to drugs
There are concerns about pollution of gene pools. For example cross pollination
from a genetically modified crop to a non engineered crop would likely result in
genetically modified rather than natural plants.
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An example of a transgenic species and why it is being produced

BT cotton is a transgenic species that was developed so further resistance to
pesticide was not encouraged and provided a cost effective way that did not
further harm the environment to eradicate the Helicoverpa Zea moth from which
the caterpillars came from.
Your conclusion of the use of transgenic species in society (should they be used)


Yes I think that transgenic species should be developed and that research should
be encouraged- however the boundary lies between knowledge and the
application of knowledge
I think that many transgenic species have the potential to benefit human society
with limited adverse affects; however the introduction into mainstream society
should not be considered lightly and must undergo many laboratory test and
ethical discussions and debates before it is approved.
Cell activity is controlled by enzymes. Enzymes are formed from chains of
polypeptides.
If the chain of amino acids forming the polypeptide is not in the right
sequence, then the enzyme formed will not be functional.
Why does Meiosis Take Places:
 ½ chromosomes for sex cells
 variation crossing over: swapping alleles
 Random segregation:
RBC= 7 UM
WBC= 12 UM
Platelets= 5-7 UM
Plasma= liquid
Capillaries:
Veins: no pumping, valve, pushes by muscles around vein, have to get rid of CO2
Blood Composition: full blood,RBCs, plasma
Which statement best describes the relationship between proteins
and polypeptide’s:
Proteins are composed of Polypeptides
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9.3 Blueprint of Life
Contextual Outline
Because all living things have a finite life span, the survival of each species depends on the ability of
individual organisms to reproduce. The continuity of life is assured when the chemical information
that defines it is passed from one generation to the next on the chromosomes.
Modern molecular biology is providing opportunities to alter the information transferred from one
generation to the next in technologies such as closing and in the production of transgenic species.
The segregation and independent assortment of the genetic information within a species provides the
variation necessary to produce some individuals with characteristics that better suit them to surviving
and reproducing in their environments. Changes in the environment may act on these variations. The
identification of mutations and their causes becomes important in preventing mutations and in
identifying and potentially nullifying the effects of mutations in living organisms.
This module increases students understanding of the history, nature and practise of biology, the
applications and uses of biology, the implications of biology for society and the environment and
current issues, research and development in biology.
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9.3 – Blueprint of Life:
1. Evidence of evolution suggest that the mechanisms of inheritance, accompanied
by selection, allow change over many generations:

Outline the impact on the evolution of plants and animals of:

–
Changes in the physical conditions in the environment:
–
Changes in the chemical condition in the environment:
–
Competition for resources:
Analyse information from secondary sources to prepare a case study to show
how environmental change can lead to changes in a species:
–
Evolution is the process of change that occurs in living organisms over many generations. It is a result of natural
selection of favourable characteristics/variations in a species so that the species is more suited to its environment
and thus more likely to survive.
–
Changes in the environment of living organisms can lead to the evolution of plant and animal species.
–
Changes in the Physical Environment:

Changes include:
 Sea levels
 Temperature, wind and amount of rainfall
 Splitting of continents

Example, the Peppered Moth (Biston Betularia):
 Prior to the Industrial Revolution of the late 18th Century, there existed 2 main types of moths, the majority of
the Peppered moths were light coloured form, whilst the lesser were black. The white moths survived better, ie
had a selective advantage as they could camouflage against the white lichen on the trees. The black variety
could be more clearly seen by predators, so their overall numbers were low.
 Post-revolution, physical changes by the pollution caused the trees to blacken with soot, and as this soot spread,
much of the light coloured lichen that grew on trees died off, leaving trees dark. The trees could no longer hide
white moths. The darker variant of the moth was better able to hide, and so the population of the peppered moth
shifted from mainly white to mainly dark.
–
Changes in the Chemical Environment:

Changes include:
 pH levels of water
 Soil salinity (not all plants are salt tolerant)
 Pesticide/poisons

Example, Mosquitoes (Anopheles) and DDT:
 When DDT (dichloro-diphenyl-trichloroethane) was first used as an insecticide to kill malarial mosquitoes, low
concentrations were effective.
 In subsequent doses, higher concentrations were needed and the sprayings became less effective.
 A select few from the population were naturally DDT-resistant that had survived, these then reproduced and
passed on their resistance gene to their offspring, as a result the majority of the mosquito population is mainly
resistant to DDT

Example, Bent grass and heavy toxic metal waste:
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 In mining areas of Wales, some areas of soil got contaminated by heavy metal waste. The bent grass grew in
both the unpolluted and polluted areas.
 Over a number of generations, the populations on polluted areas became a whole different species.
–
Competition for Resources:

Competition for resources affects evolution because the survival of a species relies heavily on its ability to obtain
the resources needed for life.

Resources are limited in an environment. The number of offspring produced by organisms is far greater than can
be supported in an environment. This causes competetion for survival within species and between differing
species.

Example, dinosaurs and mammals:
 During the Cretaceous period, the dinosaurs were dominant life forms on Earth, mammals were very scarce.
 The dinosaurs had access to most of the resources and so mammals were unable to proliferate.
 When the mass extinction of the dinosaurs occurred, the mammals that so scarcely populated the planet quickly
diversified to take advantage of all the available resources, such as plants, or other organisms.

Example, flycatchers (type of bird) and prey:
 The leaden flycatcher and the restless flycatcher both feed on similar insects but they feed in different manners.
 The leaden flycatcher catches or collects insects from trees. But the restless flycatcher hovers above the ground
and emits a call that disturbs insects. It then pounces on the insect and feeds on it.
 The ancestors of the flycatcher had feed in a similar manner, but as competition occurred, different species of
flycatcher evolved occupying different niches.
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
Describe, using specific examples, how the theory of evolution is supported
by the following areas of study:
–
Palaeontology;
including
fossils
that
have
been
considered
to
be
transitional forms:
–
Biogeography:
–
Comparative embryology:
–
Comparative anatomy:
–
Biochemistry:
–
Evolution cannot be proved, its is a theory in which cannot be experimented, this is because evolution occurs over a
million of years, however it can be supported by an array of evidence, including:
–
Palaeontology:

Palaeontology is the study of fossils, which are traces of paste life, fossils found in rocks lower down are older
than fossils found closer to the surface (unless folding has occurred).

Because fossils can be aged, the sequence from the very earliest life to the present can be observed, this is called
the fossil record, which show a clear change from simple to very complex organisms, which suggests a change
over time, which is evidence of evolution.

Example, Horses:
 Early horses (Hyracortherium) were small animals with four toes and a small check span. Fossils have been
found of horses (Mesohippus) with medium size, three toes and intermediate cheek span size. Today the
modern horse (Equus) is large with only one toe, and large check span. Fossil record shows that in horses there
has been a general trend to large size, reduced of toes and larger check span.
–
Transitional Forms:

Transitional forms are type of fossils, whose features place them between different groups of organisms, that is
they are an intermediate between a one group of organisms evolving into another. Proving evolution, examples:

Crossopterygian (lobe-fin) fish, (supports the theory that amphibians evolved from fish):
 Fish that could absorb oxygen from air appeared 40 mya
 It is thought that amphibians developed along this line of descent
 A special feature is that it had bones in its fins, which suggests it could drag itself on the land.
 FISH features: scales, fins, gills
 AMPHIBIAN features: lobe-fins (ie bones in fins), lungs

Archaeopteryx (supports the theory that birds evolved from reptiles):
 This was a small flying dinosaur with feathers, its fossil is 150 million years old.
 It appeared in the late Jurassic
 It shared features with both birds and reptiles, suggesting that birds evolved from these reptiles
 REPTILE features: long-tail, claws, no keel, solid bones, teeth
 BIRD features: wish-bone, feathers, attaches for flight muscles on the sternum (breast bone).
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–
Biogeography:

Biogeography is the study of the geographical distribution of living things. It looks at the pattern of distribution
of present-day organisms and fossils from the past.

The distribution patterns provide evidence that species have originated from common ancestors and when isolated
by physical barriers (preventing interbreeding) have evolved and become new species with often only small
differences between them. Examples:

Waratah:
 Three differing but closely related species of Waratah (Telopea) have been found in Australia, Papa New
Guinea and South America, suggesting that they each evolved from a common ancestor.

Wallace Line:
 When Alfred Wallace was working in Indonesia he noticed differences between the flora and fauna of Bali and
Lambok, despite the close distance between the 2 islands.
 For example, Bali had birds common to Asian, but Lombok had Australian parrots.
 Wallace purposed Wallace’s line, it is hypothetical line between Bali and Lombok marking separation of
Australian and Asian faunas. He suggested this change occurred because Australia had separated from Asia
before placental mammals (mammals that bear live young) evolved. So, the Australian type had thrived in
isolation, whilst those in Asia had been outcompted by mammals and became extinct.
–
Comparative Embryology:

Embryology is the study of embryos (early stage of development for eukaryotic organisms) and their
development.

The embryos of different vertebrates are very similar in their early development. In fish, amphibians, reptiles,
birds and mammals all show the presence of gill slits, tails and muscle blocks.

The gill slits develop into:
 Gills for fish, external gills for amphibians, for vertebrates no further formation occurs, however for mammals
develop into part of the Eustachian tube (an airway that connects the ear with the throat).

As for the tail, it develops in fish, amphibians and reptiles but is greatly reduced in birds and humans.

The embryos of many different vertebrates is very similar, this suggests that these vertebrates evolved from a
common aquatic ancestor.
–
Comparative Anatomy:

Comparative anatomy is the study of the differences and similarities in structure between different organisms.

If organisms are more closely related, then there should be more similar in structure then to other organisms that
separated further back in time, ie a degree of evolutionary relatedness (phylogeny).

One anatomical feature that is prominent are, Homologous structures which are those in common a between
organisms is evidence of similar inherited characteristics from a common ancestor. Examples of homologous
structures:

Pentadactyl Limb:
 It is a 5-digit limb structured bone that is found in many vertebrates such as frogs, whales, dogs, bats and
humans. This suggests that they shared a common ancestor.
 Each limb consists of one bone in the upper part, then ten two bones in the lower limb leading to 5 digits
(fingers or toes).
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 It is believed that this limb was inherited from an aquatic ancestor.

Vestigial organs:
 They are organs thought to be evoluntionary remnants of body parts from their previous ancestors, that no
longer appear to have any function in the organism, and are greatly reduced.
 For example whales have parts of the pelvis and leg bones that are remnants of their four-legged ancestor.
 Also the human appendix (reduced caecum) organ no longer used in digestion and reduced tail (coccyx) is a
vestigial.
–
Biochemistry:

Biochemistry is the study of the chemical processes in living organisms. It deals with the structures and functions
of cellular components such as proteins, carbohydrates, lipids, nucleic acids and other biomolecules. By observing
the similar biochemistry of organisms, it shows that they originated from a common ancestor.

Organisms share the same biochemistry, ie:
 Share a common genetic code of DNA or RNA
 Consist primarily of organic compounds (ie proteins, amino acid sequences and haemoglobins)
 Rely on enzymes to control chemical reactions
 Share the same cell membrane structure
 Rely on cellular respiration to make energy for cell processes.

The amino-acid sequence of certain proteins found in many organisms (such as haemoglobin and cytochrome-c)
has been analysed across a range of organisms, or similarities in the base-pairing of DNA strands have been
analysed to show evolutionary links between organisms, the number of differeneces is proportional to the length
of time since they separated.

Explain how Darwin/Wallace’s theory of evolution by natural selection and
isolation accounts for divergent and convergent evolution:
–
Recall: In 1858, both Charles Darwin and Alfred Wallace proposed the mechanism for evolution.
–
The mechanism of natural selection is based on 4 main points:

There are variations within every population of species

Organisms that don’t reproduce have their genes removed from the population

Organisms that survive and reproduce are well suited to their environments

Favourable variations are passed onto offspring and become common
–
Divergent Evolution:

Also known as adaptive radiation, it is the process whereby one species radiates out into different environments
and as a result produces organism that reach such a degree of differentiability that they no longer can interbreed,
they forms different species (speciation).

For example, Darwin’s finches:
 14 different species where described; all with similar greyish-brown to black feathers and all had similar
calls, nests eggs and courtship displays. However, their habitats, diets, body size and beak sizes differed
throughout.
 They were believed to be from mainland South America, and came on the following islands, as the islands
separated, each island had different conditions and the population evolved in isolation, they were no longer
able to interbreed.
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–
Convergent Evolution:

Also known as evolutionary convergence, it is the process whereby different organisms are subjected to the same
environmental conditions (ie selective pressures) and over the course of time evolve to develop similar
adaptations (similar physical/physiological responses), even though they may be unrelated.

For example, the seal and the bottle nose dolphin both live in the ocean:
 They have flippers as limbs, they are strong swimmers, can hold their breath longer than most mammals, and
they have a layer of fat under their skin.
 But they belong to different orders of mammals and are unrelated.

Another example includes:
 Australian marsupial (have pouch) mammals have similar outward appearance to placental (no pouch)
mammals from other parts of the world. Although they are not closely related, they live in similar enviroment
and by evolution has led to similar characteristics.
 For example, thylacines resembled wolves; sugar gliders are very similar to flying squirrels.
–
How divergent evolution and covergent are brought about:

For a new species to evolve, groups of organisms need to become isolated from each other, usually these
organisms become separated by a physical barrier (it can be created by a difference in food preference, to the
splitting of the continents).

Natural selection acts differently on each isolated population, as there are different environmental conditions and
selection pressures. Within each separate population, different mutations occur, and therefore, different variations
are produced.

Gather information from secondary sources to observe analyse and compare the
structure of a range of vertebrate forelimbs:
–
The similarities between the different pentadactyl limbs of these different vertebrates can be seen.
–
They all consist of a forearm bone, connected two a dual lower arm group, connected to wrist bones (carpals in
humans) which connect to the digits. Usually 5 in number (pentadactyl).
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–
Most land vertebrates show a similar basic pattern in the bones of their arms and legs. It is believed that they
inherited this from a common ancestor, possibly the lobe-finned fish (crossopterygian).

Use available evidence to analyse, using a named example, how advances in
technology have changed scientific thinking about evolutionary relationships:
–
Previously relationships between organisms were worked out by similarities in anatomical features.
–
New technologies, especially in the field of biochemistry, have increased knowledge about the relationships
between species.
–
DNA Hybridisation:

DNA hybridisation is a process by which the DNA of different species can be compared

The process uses heat (~90-94°C) from a thermal cycler to separate the double-stranded DNA molecule
lengthwise to expose nucleotide bases on each individual strand (dissociation).

One of these strands of the double helix, is obtained from 2 different species wished to be compared.

The single strands of the different species are then combined (re-associating) and form a ‘hybrid” (mixed) DNA
molecule, and cooled.

On cooling, the hydrogen bonds re-form in varying degrees, the greater the number of bonds between the strands,
the greater binding of strands, ie a greater degree of genetic similarity between the two species.

Heat is once again applied, this time to determine how strongly the bases have combined, higher temperatures are
required to separate hybrid strands that are more strongly combined. Closely related species have a very similar
order of nucleotide bases and so their DNA strands combine more strongly than species that are distantly related.
–
Primate Evolution, an example of evolutionary relationship:

Primate evolution was previously based on anatomical and physical features, as the growing scientific advances
have been developed, the classification has changed.

It was previously thought that chimpanzees were more related to gorillas then humans, this was based on
structural anatomy of the hind-limb “knuckle walking” and the enamel on their teeth, these studies showed that
gorillas and chimpanzees were more closely related to each other then humans.

Though through the technological advances, in 1970s amino acid sequencing was used, it was shown that
chimpanzees are more closely related to humans, then they are to gorillas. DNA hybirdisation has been used and
shown humans and chimpanzees have a base difference in their DNA by (1.6-2.4%).

This has lead to a completely different evolutionary tree, gorillas chimpanzees and humans were put in the same
family , they were in complete difference families before technological advances, also the tree shows humans and
chimpanzees as two groups diverged most recently from a common ancestor, whilst gorillas appear to have
diverged slightly earlier.
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
Analyse information on the historical development of theories of evolution
and use available evidence to assess social and political influences on these
developments:
–
Historical Development of theories of evolution:

For thousands of years, people accepted that living organisms didn’t change. There was no need to explain
evolution until evidence that organisms have changed became overwhelming (eg from fossils)

There are about 8 scientists that had the most effect on the “theories of evolution”, they include:

Leonardo Da Vinci:
 Made geological and palaeontologic observations of rocks and fossils in mountains north of Italy.
 These fossils were mostly extinct Cenozoic molluscs.
 He hypothesised these once-living shell fossils had once been living things and that they have been buried at
times before the mountains where raised instead of “biblical floods” that had washed the molluscs there.

Robert Hooke:
 Observed fossils under the microscope, and concluded that shell-like fossils were “shells of once existed
shell-fishes’.
 He also observed many fossils represented extinct organism, and poised questions at there sudden
disappearances.

George-Louis Buffon:
 He was believed to be the first to publish a ‘detailed’ booked on evolution. It was called “Les Epoques de Ja
Nature” (1788).
 It suggested life was older then 6000 years as suggested by the Bible.
 Also in one of his 44 volume publication “Histome Naturelle”, he proposed that organisms changed.
However he did not suggest how or the influences of the enviroment.
 He goes down as the “pavement” for the theory of evolution.

Carolus Von-Linnaeus:
 Through observations of organisms, and specifically hybrids, suggested that new species could evolve from
these processes.
 Thus he founded the binomial (two) name system. And fought the idea that species had changed and believed
(wrongly) that all were created together and non had become extinct. This idea he later changed at the end of
his life.

Erasmus Darwin:
 He was a leading naturalist that formulated the first modern theory of evolution in his book “The laws of
organic life”.
 It described how one species could evolve into another, through process such as sexual selection and
competition.
 Also introduced the concept of ‘adaptation’, which states organisms are for enviroment when there structure
reflects the functions that are needed by that enviroment.

Jean-Batiste de Lamarck
 He proposed that evolution was carried out by 2 driving forces:
 Change in animals from simple to complex organisms
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 Adaptation of animals to an enviroment leads to their differences.
 This was the basis for evolution, however he incorrectly proposed that features acquired during the life of an
organism could be passed on to its offspring. An example used to support this, was the long necks in a
giraffe. It long neck is passed onto to its offspring.
 This lead to the continuation for “natural selection” and was a major contribution.

Alfred Russel Wallace
 He was interested in collecting specimens of plants and animals. He travelled to South America, and Malay
Islands.
 He provided proof of evolution through biogeography. Through this the imaginary line that separates the
fauna of Asia and Australia was named “Wallace line”.
 He independently arrived to the same conclusions of Darwin, and formed the theory of evolution.

Charles Darwin:
 He was influenced Jean-Batiste Lamarck and other scientists, and thus spent most his lifetime understanding
these principles.
 Went on the ‘beagle’ to travel around the world, and aquired a lot of his information from the “Galapagos
islands”, notably where he found the soon to be “darwin finches”, that propelled his theory.
 Spent more then 20 years, studying specimens. Questioning their orgins, comparing variation, experimenting
and writing his theory.
 Published the book “On the origin of species” (1859). Which described the theory of evolution in detail.
 It consisted of 2 major points,
–

Species were not created in modern form,

Natural selection was the mechanism for their change.
Influences Prior To Publishing of Evolutionary Theory:

Science is greatly influenced by society, and in general how the world is viewed.

The world views are in turn influenced to a large extent by politics, which determine to a large extent by politics
that determines the framework that governs everyday life.

Christianity was a very dominant force during the time of Charles Darwin.

Creationism was widely accepted, as a religious and a scientific concept.

Darwin knew what a huge impact his knowledge would make on the world when he released it, so he withheld his
theory for 25 years.

It was only when he felt the social and political climate was right, and the face that Wallace had wanted to publish
his theory after formulating and analysing it, did he publish his information

He chose to publish it during a time of great societal change; i.e. the Industrial Revolution, and a time when the
power of the Church was weaning.

Also, Wallace’s willingness to propose his own version of evolution prompted Darwin to finally publish his
papers Darwin’s ideas caused a revolution in scientific thought. At the time it was generally believed that that the
Earth was 6000 years old and that each species had been individually created in its present form by God. The
theory of evolution suggests change in organisms over millions of years.

The predominant view in western cultures, up until Darwin’ theory was creationism – the diversity of living
things was created for the environments at he same time by God in six days; the organisms have not changed and
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Page 10 of 45
are not related. People believed that humans had a special place in the world; that they were Gods creation and the
world was made by him for them. The idea of evolution reduces humans to the same level as every other
organism and threatened the basis of their power. It also threatened the power of the religious institutions that had
long held political and social power, by giving importance to scientific thought.

In spite of mounting scientific evidence, Darwin’s theory of evolution was and still is rejected by many religious
people. Darwin’s theory, particularly the idea that humans are descended from apes, caused social and political
outrage. In the 1920’s Protestant traditionalists campaigned against the anti-biblical ideas of evolution. Several
states in the USA passed laws banning the teaching of evolution in public schools.

In 1925 a teacher from Tennessee, John Scopes, was arrested and put on trial for teaching the theory of evolution
to his class. The Scopes trial is famous in America, it was a confrontation between fundamental Christians and
evolutionists and between opposing politicians and lawyers. In 1968, the US Supreme Court ruled that laws
banning the teaching of evolution were unconstitutional. Social and political forces still exist in some
communities today and exert pressure on schools to teach the Biblical story of Creation.

The theory of evolution causes political and social reactions that few other biological theories do. At the same
time of its publication, there were many cartoon publishing ridiculing Darwin and his theory.
–
Influences of Evolutionary Theory on Society:

Darwin’s theory caused great furore in the society at the time. Great debates were fought out by evolutionists and
creationists (a famous one being between Thomas Huxley and Bishop Samuel Wilberforce).

Darwin was also blamed for many catastrophes in history, as people continued to wrongly apply the “Survival of
the Fittest” to normal life.

Darwin has been blamed for the destruction of religion and the rise of atheism, fascism, communism and even the
Second World War, as people like Karl Marx base their philosophies on The Origin of Species.
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
Plan, choose equipment or resources and preform a first-hand investigation to
model natural selection:
–
Aim: To model the process of natural selection.
–
Equipment:

100 different coloured (green, red, white, blue) of large buttons

Stop watch
–
Safety:

Sun has strong UV light outside, sunscreen and hats should be worn.

Grass can have splinters and can be sharp, gloves should be worn.
–
Method:

In a 15 metre by 15 metre grass square, buttons where randomly thrown out in the ground

In 10 min, the buttons where to be found.
–
Result:

Many colours where found in complete numbers (100 buttons), but over 50 of the green where lost.

The red, blue, white buttons against the green background would be found in greater numbers as they would not
have a selective advantage over the green toothpicks due to the camouflage effect.

Thus the green compared to the environment, had a better-adapted organism that will go on to reproduce in
greater numbers, over time the green organisms will become the more prevalent phenotype within the organisms
population.
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2. Gregor Mendel’s experiments helped advance our knowledge of the inheritance
of characteristics:
 Outline the experiments carried out by Gregor Mendel:
–
Darwin and Wallace proposed their theory of evolution, but they did not know the mechanism for inheritance of
these characteristics.
–
Gregor Mendel, is the founder of the modern study of genetics (heredity), was an Austrian monk.
–
In 1856 he carried out experiments to study the genetics of the garden pea plant (Psium sativum) and how certain
characteristics were inherited from one generation to another.
–
Mendel’s Experiment:

Before he began his experiment, he selectively bred plants for each characteristic for 2 years to produce ONLY
pure breeding offspring

Then he preformed cross-pollination experiments with pea plants that differed in one trait, for example pod color.

Mendel then chose 7 pairs of characteristics that he wanted to study

These were:
–
round/wrinkled seed (seed shape)
round/wrinkled seed (seed shape)
yellow/green seed (seed colour)
smooth/constricted seed pods (pod shape)
green/yellow pods (pod colour)
violet/white flowers (flower colour)
tall/short stem (stem height)
terminal (at the top) / auxiliary (off the sides) flowers (flower position)
He did this by manually transferring pollen from the anthers (male part of plant) of one pure breeding plant to a
contrasting pure breeding plant, BUT he removed the anthers from this contrasting pure breeding plant so that plant
did not self-fertilise (plants have both male and female sex organs on the same plant). These then produced seeds,
which he planted to obtain the required plant.
–
He firstly crossed two pure breeding plants, then crossed their off-spring.
–
Mendel then put forward his laws:

Random segregation: each pair of a homologous chromosome is sorted independently during meioses in sex cells.

Independent assortment: principle that during meiosis two copies of each genes are created then distributed to the
sex cells independently of the distribution of other genes.

Describe the aspects of the experimental techniques used by Mendel that led
to his success:
–
He chose the pea plant that shows easily identifiable, alternative forms.
–
He made sure he used pure breeding plants, he controlled his experiment.
–
He studied separate, easily identifiable characteristics, one at a time, not the whole plant.
–
He studied a large number of characteristics.
–
He performed a large number of crosses (~29000 altogether); i.e. he repeated many times.
–
He made exact counts of the characteristics, producing quantitative data that could be easily analysed.

Distinguish between the terms allele and gene, using examples:
–
Every organism is made of billions of cells, in a cell their exists specific organelles, such as ribosomes,
mitochondria, nucleus and so on. Specifically in the nucleus their exists chromosomes, it is a X looking structure.
–
Different eukaryotic (nucleus containing) organisms have different numbers of chromosomes, humans have 46
chromosomes, whilst cats have 38 and so on.
–
A chromosome is composed of 40% DNA (set of codes), and 60% protein.
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–
A gene is a very small locus (ringed area) on a chromosome, in that ring is a “set” of DNA, these are what code for a
specific characteristic (note: millions of genes make up a chromosome).
–
A gene itself partially codes for a specific characteristic. However 2 genes MUST be present to completely code for
that characteristic.
–
When the mother and father of an organism mate, the sperm and egg fertilise to form that organism. These egg and
sperm are known as sex cells (also gametes), they are formed in the male and female genitalia respectively by
meioses. Meioses is the process in which normal body cells are converted to sex cells, but in the process half the
number of chromosomes. Ie the original number is 46, it then becomes 23 in each sex cell.
–
So the mother and father each have 23 chromosomes in their sex cells respectively, when these fertilise to form that
organism, the two combine and create 46 again.
–
Every characteristic that a human contains is coded by 2 genes, one gene from the mothers set of 23, and the other
gene from the fathers set of 23 chromosomes.
–
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–
So genes always come in a pair, one from the mother (maternal) and one from the father (paternal), these pairs of
genes are on chromosomes that are called HOMOLOGOUS chromosomes.
–
Now for a specific characteristic, example hair colour, 2 genes are required for this, however, not all genes are the
same, if this was so then everyone would have the same hair colour, there are different types of genes.
–
Genes are a locus (ringed area) on the DNA, this DNA is coded by a specific set of bases, which codes for a
particular characteristic. A gene elsewhere, with the SAME locus, that has a different set of bases which code for a
different characteristics is known as allele. That is; alleles are alternative DNA sequences at the same physical locus.
–
So by definition an allele is different/variant/alternative forms of genes. (note: despite an allele being variations of a
gene, IT IS STILL A GENE)
–
Eg. The gene for eye colour, and the brown allele or the blue allele.

Explain
the
relationship
between
dominant
and
recessive
alleles
and
phenotypes using examples:
–
The genotype of an organisms is its genetic make-up, ie the 2 genes required to make that characteristic, genes are
represented by single alphabet characters. Example a black gene (or allele) is B.
–
The phenotype is the physical characteristics of an organism, ie it is what is formed when genes combine to give
that characteristic.
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–
Dominant and recessive alleles:

For every characteristic, there are 2 genes, ie 2 alleles.

One of the alleles is always DOMINANT, and one of them is RECESSIVE. Ie one of the allele is superior over
the other.

The dominant allele is usually capatilised, whilst the recessive is de-capatilised in terms of alphabet, for example
the allele for dimple smile (S) is dominant over the recessive normal smile (s).

If the two genes (alleles) are the same, then the organism is said to be homozygous for that characteristic.

If the two genes (alleles) are different, then the organism is heterozygous for that characteristic.

When an organism is homozygous (ie 2 same alleles), the phenotype is represented as either allele.

When an organism is heterozygous (ie differing alleles), the phenotype of the dominant allele is represented.

Taking a characteristic, e.g. Dimple face from above. We represent it’s genotype with 2 letters, each letter
representing a gene. B is the dominant dimple smile allele, b is the recessive, normal face allele

A dimple face can be either BB or Bb, as the dominant gene is always expressed

A short plant is always tt, nothing else.

Solve problems involving monohybrid crosses using Punnett squares or other
appropriate techniques:
–
T
t
T
TT
Tt
t
Tt
tt
A punnet square is a simple method of showing the genotype and phenotype
of certain crosses, it has a top row for maternal and side coloum for pateral
genes.
–
Example of a punnet square:

Genotype: TT, Tt, tt

Phenotype: 3 tall (TT, Tt, Tt) and 1 short (tt)
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
Describe
outcomes
of
monohybrid
crosses
involving
simple
dominance
using
Mendel’s explanations:
–
Mendel’s Monohybrid Crosses:

Mendel only studied one pair of characteristics at a time (e.g. stem height)

Mendel first bred one variety of pure-breeding plant (e.g. tall plants) with another variety, also pure-breeding (e.g.
short plants).

The parents were cross-pollinated, and all the off-spring was tall. (F1 is known as the first filial generation)

Parents:
Homozygous tall plants (TT)
F1:
Genotypic Ratio: Tt
x
Homozygous short plants (tt)
Phenotypic Ratio: all tall plants [As the dominant gene is always expressed]

Mendel then took these heterozygous tall offspring and self-pollinated them:

F1:
F2:
Heterozygous tall plants (Tt)
(approximately)
x
Heterozygous tall plants (Tt)
Genotypic Ratio: 1 TT : 2 Tt : tt
Phenotypic Ratio: 3 tall plants: 1 short plant

Mendel repeated this experiment many times, and with different characteristics such as seed colour, but the same
ratio kept occurring.

–
The F2 ratio 3:1 is called the monohybrid ratio.
Mendel’s conclusions about these experiments are summed up in his Law of Segregation:

An organism’s specific characteristic are determined by two ‘factors’ (genes).

In a sex cell (haploid gamete), from each parent, only one ‘factor’ is present.

During fertilisation, the ‘factors’ (genes) pair up again; they don’t blend, but match up with each other
–
Extra:
–
However in an organisms you don’t only have 1 characteristic, you inherit many, for length, hair colour, body
stature etc. Mendel began to wonder what would happen if he studied plants that differed in two traits. Would both
traits be transmitted to the offspring together or would one trait be transmitted independently of the other.
–
Mendel examined specific and double-specific characteristics during his experiments, ie a monohybrid cross is
where only one characteristic is examined (one pair of genes), a dihybrid cross is where two characteristics are
considered (two pairs of genes).
–
Mendel experiments involving two or more characteristics at a given time:

Before he carried out his experiments, he made sure that the plant was PURE-BREEDING for two characteristics.

For example, a plant that had pure-bred (homozygous) green pod color and yellow seed color was cross-pollinated
with a plant that had yellow pod color and green seeds. In this cross, the traits for green pod color (GG) and
yellow seed color (YY) are dominant. Yellow pod color (gg) and green seed color (yy) are recessive.

The resulting offspring (F1 generation) were all heterozygous for green pod colour and yellow seeds (GgYy).
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
After observing the results of the dihybrid cross, Mendel allowed all of the F1 plants to self-pollinate.

He then assumed the possible genotypes of the gametes from the GgYy pea plant is: GY, Gy, gY, gy. Then he
again hypothesized the ratio when these gametes formed to create the new organism, thus proved his hypothesis,
which makes his law valid.

Mendel noticed a 9:3:3:1 ratio. About 9 of the F2 plants had green pods and yellow seeds, 3 had green pods and
green seeds, 3 had yellow pods and yellow seeds and 1 had a yellow pod and green seeds.

From these experiments Mendel formulated the law of independent assortment. This law states that allele pairs
separate independently during the formation of gametes. Therefore, traits are transmitted to offspring
independently of one another.

This means only 1 allele is allowed in a gamete (as maternal and paternal chromosomes split), G cannot be with g
in a gamete.
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
Outline the reasons why the importance of Mendel’s work was not recognised
until some time after it was published:
–
Mendel’s work was published in 1866, yet the importance of his work was not recognised for almost 35 years, until
some time later (1900).
–
The reasons could be:

His work was radically different to previous ideas, at that time very little was known about cells; chromosomes;
mitosis and meiosis, ie the studies of genetics in general, hence he was possibly not understood.

Significance was possibly not realised at the time, his work was radically different, most scientists accepted the
belief at that time, that blending of characteristics occurred, ie a tall and short couple would given a middle
heightened sibling.

He only presented his paper to a small group of scientists.

He had no outstanding reputation as a scientist, and no prior significant research, as a result his standing as a
scientist would be ‘doubted’, meaning possible ignored by scientific community.

Perform an investigation to construct pedigrees or family trees, trace the
inheritance of selected characteristics and discuss their current use:
–
Pedigrees are family trees; they are essentially a graphical mean of describing genetic traits. They show the
inheritance of a particular characteristic over many generations. These charts are drawn up in a universally accepted
scientific format, using standard symbols. They show an individual’s biological relatives and their partners as a
series of circles and squares, linked by lines. The occurrence of a particular trait is shown by shading (it can be
negative OR positive, it does NOT matter).

Note: pedigrees used for autosomal inheritance, and later in the topic for sex-linked, co-dominance inheritance.
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–
A typical setup, roman numerals represent generation number, the arabic numberals signify individuals, in order of
birth. So individual II-2, is the second born child in generation II.
–
Patterns to recognize:

If two non-affected parents have an affected child, then the trait is a recessive one.
 This is because, the ‘non-affected’ parent MUST somehow carry the gene for a recessive trait, there is no
possible way to obtain a trait without having it, however since both are parents are ‘non-affected’ by this trait, it
MUST be recessive and is masked by some other prevalent trait, however in their formation of child, the
probablity of those two affected traits increases and hence a homozygous recessive child.

If two affected parents, have a non-affected child, then the trait is dominant.
 The only way to obtain a non-affected child from a affected parents, is if both parents are heterozygous for a
trait, hence they are carrying a ‘recessive’ gene, that is masked by the ‘dominant’ gene, when the form the child
though, the recessive gene can match up with another recessive gene, hence being non-affected.

For sex-linkage (discussed later): if there is a large bias towards males being affected, and sometimes
generations are skipped, than the trait is recessive sex-linked.
–
Note: Regardless of autosomal or sex-linked pedigrees, skip generation generally refers to a generation two or
more generation below a person, this ONLY occurs in recessive autosomal traits AND sex-linked recessive, nothing
else.
–
The current use of pedigrees:
–
Pedigree charts allow an easy scientific analysis of the inheritance of genetic traits within families and are useful for
studying heredity patterns in humans and other animals. It would be ethically unacceptable to carry out controlled
breeding or test crosses to determine a genotype in humans.
–
In humans, most pedigrees are analysed to identify and trace genetic disorders; in animals, they are useful for
selecting individuals with desirable traits for breeding purposes.
–
Human pedigrees

By assigning genotypes to indivudals and making predictions from pedigrees, they can be used to:
 Determine if particular family traits are genetically inherited
 Trace the occurrence of a gentic disorder, abnormality or disease within a family over several generations.
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 Deduce genotypes, that is to determine the probablity that prespective parents are heterozygous for a particular
defective allele (that is they are carriers).
 Predict the likelihood of a family member inheriting a trait or developing a disorder.

Advantages:
 Can be used by genetic counsellors to advise parents on minimising or avoiding the risks of producing a child
with the defect.
 Help researchers develop a program to eliminate the inherited defect in the population, researches use pedigrees
to identify and study what gene causes a disorder, and then select only those individuals that are at risk, to limit
the gene in the population. For example pedigrees were used in Australian breast cancer studies, to reveal
individuals that have a low-risk genes that may increase probablity of a person getting breast cancer when in
combination with another person of the same type.
–
Animal pedigrees:

Select suitable individuals by identifying any desirable traits.

Predict the distance in relatedness (hence genetic difference) between 2 organisms. A pedigree index is calculated,
basted on distance in relatedness of parents and this is assigned to offspring. Offspring that are distantly related
tend to be healthier then inbred organisms.

–
Verify thoroughbred status of animals by breeding societies.
Limitations of pedigrees

Pedigrees are only useful when studying animals that do not produce too many offspring, eg mammals.

In humans, the usefulness of pedigrees relies on accurate and reliable record-keepying within familes (eg
deceased relatives). This may cause catstrophical results if a couple get ill-information and decide not to have
children due to simple mistake.

Process
information
from
secondary
sources
to
describe
an
example
of
hybridisation within a species and explain the purpose of this hybridisation:
–
A hybrid means formed from two. It can be anything from, DNA-DNA hybrids (such as strands of DNA from a
chimpanzee and a strand from a human), or a combination of plants. Depending on the context it is used.
–
However in general, Hybridisation means the breeding of two different types of plants or animals. For example, a
mule is the result of the union between a horse and a donkey. The resulting animal has desirable characteristics from
both parents.
–
An important example, especially in horticulture (which is the industry and science of plant cultivation), is the food
crop known as Triticale. It is formed by the crossing of the wheat species Triticum turgidum, with a rye plant
Secale cereale.
–
–
This plant is:

Fertile (can reproduce)

High yielding

Drought tolerant

Can grow in unfavourable wheat growing conditions

Disease resistant
All the above characteristics are what is known as hybrid vigour, which is the condition that describes the added
strength that comes crossing organisms that are not genetically similar.
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3. Chromosomal structure provides the key to inheritance:
 Outline the roles of Sutton and Boveri in identifying the importance of
chromosomes:
–
Recall: Mendel did not known about genes, he knew some mechanism, where “factors” were working, but what
exactly was occurring he did not know.
–
2 scientists through there experimentation helped in identifying mechanisms, but again did not find what these
“factors” where.
–
They both worked independently, but reached similar results; hence both are given the credit for their work.
–
Theodor Boveri:

Boveri, a German cytologist (branch of biology that deals with the formation, structure, and function of cells).

He carried out experiment on sea urchin and their eggs in 1902.

He studied the behaviour of the cell nucleus (and its chromosomes) during meioses and after fertilisation.

At the time it was known that each living organism had a set number of chromosomes, and at fertilisation the egg
and cell fuse. But a wrong common belief was that protein was the hereditary material, because protein was found
in the cytoplasm and nucleus.

His experiment showed:
 When a normal egg and sperm fused, the organism showed characteristics of both parents.
 If the nucleus of only one parent was present (example sperm), the larvae resembled that parent (being male),
but, was abnormal both physically and physiologically.
 Hence he disapproved that protein was the hereditary material, this is because it would not matter if one nucleus
was removed, the protein can make copies, but the organism was defected.

Boveri’s experiment showed that:
 The nucleus of the egg and sperm each contribute 50% of chromosomes to the zygote (fertilised egg), making a
connection between chromosomes and heredity.
 A complete set of chromosomes (ie 2 chromsomes, one from each parent) is needed for normal development.
 The “factors” which are found on chromosomes are the carriers of heredity.
–
Walter Sutton:

Sutton, an American cytologist

He worked on grasshopper testes.

He specifically studied the chromosomes in meioses.

His experiment showed:
 At the beginning of meioses (prophase 1), chromosomes occur in distinct pairs in cells. One is paternal and the
other maternal (today known as homologous pairs). These chromosomes are exactly the same shape and size.
 During the process of meioses, chromosomes need to be halved, as there is 46 chromosomes, 23 are
homologous pairs these segregate from each other and make a duplicate of themselves so that each of the 4
gametes created from meioses receives one chromosome from each pair.
 After fertilisation, the resulting zygote had a full set of homologous chromosomes

Suttons experiment showed that:
 He suggested Mendel’s inheritance ‘factors’ (genes) are carried on chromosomes and behave in the same
manner as Mendels ‘factors’
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–
Both these scientists, through independent researched, proposed the same theory “Chromosome theory of
inheritance”
–
Note: The term ‘gene’ was not yet in use when both scientists proposed their theories, it was introduced 6 years later
in 1909 by the Danish Wilhelm Johannsen.

Describe the chemical nature of chromosomes and genes:
–
Each chromosome is made up of about 60% protein and 40% DNA
–
The DNA is coiled tightly around a protein core (histone proteins)
–
A gene is a section on a chromosome, made up of DNA
–
DNA is further made up made up of a particular sequence of bases
–
Different genes are different lengths (diameter of locus), hence differing lengths of DNA.
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
Identify that DNA is a double-stranded molecule twisted into a helix with
each strand comprised of a sugar-phosphate backbone and attached bases –
Adenine (A), thymine (T), cytosine (C) and guanine (G) – connected to a
complementary strand by pairing the bases,
–
A-T and G-C:
DNA (deoxyribonucleic acid):

A double stranded helix

Made up of sub-units called nucleotides, each nucleotide is made up of a phosphate, a deoxyribose sugar and a
nitrogenous base.
–

The four different nitrogenous bases are adenine, thymine, guanine, and cytosine

Adenine pairs with thymine (A-T) and guanine with cytosine (G-C)
A single DNA strand is made up of a chain of nucleotides (a polynucleotide) where the phosphate and sugar
alternate as the backbone of the strand
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
Process
information
demonstrates
meiosis
from
and
secondary
the
sources
processes
of
to
construct
crossing
over,
a
model
that
segregation
of
chromosomes and the production of haploid gametes:
–
Meiosis is the process of reductional division in which normal body cells are converted to sex cells (ie gamates), but
in the process half the number of chromosomes. Ie the original number is 46, it then becomes 23 in each sex cell.
–
Crossing over shown below:
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
Explain the relationship between the structure and behaviour of chromosomes
during meiosis and the inheritance of genes:
–
Note: Chromosomes are made of DNA. Genes are coded within the DNA on the chromosomes.
–
The stages of meiosis that lead to the creation of gametes and the inheritance of genes are:

The chromosomes (which therefore include the genes) make a complete copy of itself (duplicate). The single
stranded chromosomes become double stranded, linked at the centre by a centromere.

In the first meiotic division, the homologous chromosomes separate, but the double-strands of the chromosomes
are still joined.


In the second division, the chromatids of the chromosomes separate and form 4 gametes altogether.
Explain the role of gamete formation and sexual reproduction in variability
of offspring:
–
Gametes form by meioses, where recombination of genetic material takes place as a result of crossing over and
random segregation:
–
Crossing over: is the process in which homologous chromosomes exchange genes and so the resulting
combinations of alleles on chromatids differ from those originally on the parent chromosome.
–
Random segregation: occurs during meiosis, genes on different chromosomes sort independently. They can line up
in the middle of the cell in many different ways. This produces many gene combinations, which are different from
the parents
–
A fertilised egg, is formed when a female sex cell (egg) and a male sex cell (sperm) fuse. When this fusion occurs,
random fertilisation occurs.

Random fertilisation: is the process when a random (one of the 4 gametes) from a male and female fuse, these two
different gametes randomly fuse. Many different combinations are possible, and this causes variation.
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
Describe
the
inheritance
of
(1)
sex-linked
genes,
and
(2)
alleles
that
exhibit codominance. Also explain why these do not produce simple Mendelian
results:
–
Mendelian ratios of inheritance (ie monohybrid/dihybrid ratios) ONLY apply in situations where conditions are
similar to those studied by Mendel, where genes sort independently and one gene is dominant over an other.
However NOT all results follow this, there are deviations from Mendel’s ratios, this can be seen in sex-linked
inheritance and co-dominance inheritance.
–
Co-Dominance:

In some characteristics coded by genes in organisms, the heterozygote combination DOES NOT display the
dominant allele (example for tall/short plants, the genotype Tt displays the phenotype tall).

Co-dominance (co = together, dominance = dominant alleles) refers to the fact that the two alleles are not
dominant over each other, both alleles are expressed in at the same time.

It does not “blend”, the alleles do not mix, but, BOTH can be seen at the same time.

An example can be seen in a specific type of cattle.

If heterozygous cattle have the gene for red, and white, it would not make a pink cow, but the hairs on the cow
would be both red AND white, making a roan colour.

Looking at the cross in the form of a Punnet square, we can see that a cross concerning a codominant trait does
not give the simple Mendelian ratio of 3:1

The cross between the two roan cows of the F1 generation does not give the 3:1 ratio because a heterozygous
animal does not give the dominant trait, as would happen in simple dominant-recessive cases. A
“heterozygous” animal gives the roan colour, which results in the 1:2:1 ratio.
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
Note: Co-dominant alleles are both written as capital letters, meaning you cant have Rw as roan, that will just
be red. So the parents must be homozygous/heterozygous co-dominant alleles, it cannot be homozygous or
heterozygous normal dominance.
–
Extra: Complete/Incomplete Dominance:

Complete dominance: This is what Mendel did, it is described as the kind of dominance wherein the dominant
gene completely masks the effect of the recessive gene in heterozygous condition.

Incomplete dominance: it is also a form of dominance in which does not follow medelian ratios, it is described
as a kind of dominance occurring in heterozygotes in which the dominant gene or allele is only partially
expressed, and usually resulting in an offspring with an intermediate phenotype.

In incomplete dominance, a heterozygous organism carrying two alleles wherein one is dominant and the other
one is recessive, (e.g. Aa), the dominant allele will only be partially expressed. Hence, the heterozygote (Aa) will
have an intermediate phenotype.

In this case, if the both alleles are present, a blending of phenotype will occur.

For example if a snapdragon (a flower) has a red a white gene, it will be pink.
–
Sex-linked Characteristics (genes):

In humans there are 23 pairs of chromosomes (ie 46 chromosomes), these pairs are ordered base on pair sizes, as
in a pair both chromosomes are same size so largest being the first pair, the smallest being the last pair. However
the chromosomes in the 23rd pair is a unusual case.

All chromosome pairs are very similar in both male and female (ie pair 1-22), however in the 23rd pair it is not
similar, and this is where the sex of a male/female is decided.

In this this 23rd pair, there exists 2 chromosomes (called sex chromosomes), the first one is common to both
females and males (its is detonated as X), HOWEVER the second chromosome is NOT THE SAME (it is
detonated as X if females, and in males it is detonated as Y).

Hence the ‘sex’ of an human is determined by the combination XX (female) or XY (male).

For males, the sex chromosomes are different. The combination is XY. The Y chromosome is shorter than the X
chromosome.

Because the Y chromosome is much shorter than the X chromosome, MOST characteristic are only coded for by
the X chromosome. (there does exist few characteristics which are carried by the Y example hairy ears)
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
Also sex-linked characteristics are written as superscripts on the “sex” chromosomes (this is because they only
occur there)

Take, for example haemophilia. ‘H’ is the dominant, normal allele; ‘h’ is the recessive, haemophiliac allele
 Note: there exists recessive and dominant sex-linked inheritance, however, ONLY recessive sex-linked is ever
tested in HSC.
 Females:

A normal female’s genotype – XHXH

A carrier female has the genotype - XHXh

A haemophiliac female has the genotype – XhXh
 Males:

A normal male - XHY

A haemophiliac male - XhY

Males only have to inherit a single gene to have the characteristic.

Females, having two X chromosomes, will have a second normal gene to ‘fall back on’ even if one is deficient ie
they have a 33% chance of getting the disease.

However, males have a 50% chance of getting the disease, as only 1 gene decides what happens. Ie a single
recessive gene has the same phenotypic effect as a single dominant gene.

This is why some sex-linked characteristics are much more common in males than females.

Note: you can have a case of codominance and sex linkage in the same cross, ie the codominant genes are carried
on the sex cells.

Explain the relationship between homozygous and heterozygous genotypes and
the resulting phenotypes in examples of codominance:
–
In simple dominance cases, if an organism is homozygous dominant, the phenotype is obviously that of the
dominant allele. If it was homozygous recessive, then the phenotype would be that of the recessive allele.
–
If the organism was heterozygous, then the dominant allele would be the phenotype of the organism, as the
dominant allele would preside over the recessive one.
–
However, if it was a case of codominance, heterozygous organisms would have both phenotypes expressed at the
same time, as no allele is totally dominant over the other. Eg, red and white – roan cattle.

Describe the work of Morgan that led to the understanding of sex linkage:
–
Thomas Hunt Morgan was an American cytologist.
–
At the time, people were skeptical about the ‘chromosomal theory of inheritance’.

Morgan studied the breeding of the vinegar fruit fly (drosophila melanogaster) to see if some characteristics
followed Mendelian ratios.

He looked at crosses between normal red-eyed flies and mutant white-eyed flies and found that the results could
not be accounted for by simple Mendelian crosses.

When he crossed a white-eyed male and red-eyed female, he found that the F1 generation was all red eyes. This
suggested that the red eyes were dominant. Ie he supposed that the male was (ww) and red female was (RR), so
all offspring were (Rw) hence red eyes.

Though when he bred the F2 generation, the 3:1 ratio did not show, ie Rw X Rw = 1 RR, 2 Rw, ww.
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
Instead, he found that all females and 50% of males had red eyes. This is impossible to follow Mendelian ratios as
atleast 1 female should have been white.
–
Thus his results showed that sex chromosomes determine the sex of a fly, as well as the fact, that eye colour for fruit
flies are carried on the sex chromosomes, ie some specific characteristics are carried only on the X chromosome that
is, they are sex linked genes.

Outline the way in which the environment may affect the expression of a gene
in an individual:
–
Genes are not the only factor that influence phenotype, variations in organisms are genetically determined (nature),
but can aswell be influenced (nurture).
–
The gene expression (usually phenotype but can be internal such as haemoglobin etc) is often influenced by a
combination of the two. The environment can control to what extent a genotype is expressed.
–
Examples:

Phenylketonuria (PKU): is a genetic disorder, where babies born can not make the important enzyme phehydroxylase, and as a result, can not metabolise (breakdown) the amino acid phenylalanine (phe) into tyrosine. If
a baby eats excessive amounts of phe, the babies will become severely mentally retarded. If phe levels are kept
low, the babies will grow up normally.

Hydrangeas: is a plant that has pigments known as anthocyanins these control this flower’s colour and are
affected by pH. If the hydrangeas grow in acidic environments, the flowers will be bright blue. In alkaline
environments, the flowers are pale-pink.

Solve problems involving co-dominance and sex linkage:
–
This has been covered above. It can include pedigrees and punett squares.
–
Both co-dominance and sex linkage can follow the simple Punnet squares. When the co-dominant alleles are
present, the phenotype is midway. For sex linkage, the male only has to have the defective X-chromosomes, while
females can be heterozygous (carriers) or affected (homozygous).

Identify data sources and preform a first-hand investigation to demonstrate
the effect of enviroment on phenotype:
–
Aim: To model the effect of enviroment on phenotypes.
–
Equipment:

2 pre-packed bean seedlings

Water

Source of dark light, and light
–
Saftey:

–
The bean seedlings may have contagious diseases, gloves should be worn.
Method:

One seedling was left as a control, it was watered and taken care of normally under shade.

The other two seedlings, were placed in either light covered area, and one in dark covered area for them to
germinate.

Water occasionally and wait for observable phenotypical results.
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–
Result:

The phenotype expressed in the light ones show green pigment for the environment influenced the need of
chlorophyll for photosynthesis. While the ones in the dark turned albino, in the absence of light, photosynthesis
can not take place.

When these albino plants were put in the sun, over the course of 2 days they changed to green colour again.
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4. The structure of DNA can be changed and such changes may be reflected in the
phenotype of the affected organism:
 Describe the process of DNA replication, and explain its significance:
–
DNA replication is made possible because the molecule is a double helix, and because the nitrogenous bases only
pair complementarily (that is Adenine with Thymine, Guanine with Cytosine)
–
The steps for DNA replication:

An enzyme called hilicase causes the parent DNA helix molecule unwinds through the breaking of hydrogen
bonds between complementary bases, hence the DNA splits through the middle into 2 separate strands.

As the two strands become exposed, the enzyme DNA polymerase picks up free nucleotides floating in the
nucleoplasm (nuclear sap), and slot these into the opposite complementary base pair, meaning it attaches the
exposed bases, A with T and C with G.

The direction in which nucleotide insertion occurs is antiparallel, one of free forked DNA strand, it begins at the
replication point and goes towards the end of the strand, whereas on the other strand it begins at the end of the
single strand and goes towards the replication fork.

The joining of nucleotides (base pairs) is checked by another “DNA polymerase” enzyme, and ‘edits’ any
incorrect additions, to ensure accuracy (note: incorrect base pairing will result in a mutation).
–
The significance:
–
DNA has 2 main functions in a organism:
–

Heredity: this relies on DNA replication.

Protein synthesis through genes (which are a locus of DNA).
In hereditary: DNA must be able to make an exact copy of itself so that when a cell divides to form sex cells, the
resulting daughter cells each have a full copy off DNA. The significance of this process is the genetic information is
passed on from generation to generation. During sexual reproduction, the genetic code is copied and then half of the
genetic information passes into each of the sex cells (ovum or sperm). When fertilisation occurs the new organism
has half the genetic material from each parent.
–
Protein synthesis: DNA is necessary to make all the RNA and proteins needed for cells carry out necessary reactions
and cellular processes in order for them to survive. Genes are expressed in terms of the protein products that they
produce. Many of these proteins are enzymes, which control chemical functioning of cells. Other proteins produced
may form a structural part of the cell (eg the protein in cell membranes, pigment in skin and eyes) and some proteins
form essential chemical such as hormones (eg insulin), defence proteins (eg antibodies) and transport proteins (eg
haemoglobin); DNA directs the production of these products.

Explain the relationship between polypeptides and proteins:
–
A protein is a polymer made up of one or more polypeptide chains, folded to fit a specific function, often into a
globular shape.
–
A polypeptide is made up of amino acids linked by peptide bonds
–
The sequence of amino acids in a protein is defined by the sequence of a gene, which is encoded in the genetic code.
–
Protein
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Polypeptide
Amino acids
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
Outline,
using
a
simple
model,
the
process
by
which
DNA
controls
the
production of polypeptides:

Preform
a
first-hand
investigation
or
process
information
from
secondary
sources to develop a simple model for polypeptide synthesis:
–
DNA controls the production of proteins and polypeptides because different DNA sequences (genes) produce
different kinds of proteins.
–
The structures involved in polypeptide synthesis are:

DNA: A gene contains a sequence of bases to code for a protein

RNA: RNA is similar to DNA except that instead of deoxyribose sugar its a RIBOSE sugar. It is also single
stranded, and instead of thymine, there is uracil. There are 2 forms involved in polypeptide synthesis:
 mRNA: Messenger RNA carries the genetic code outside the nucleus, into the cytoplasm, where it can be read
by ribosomes
 tRNA: Transfer RNA carries the amino acids to the ribosomes to link and form a polypeptide chain. tRNA are
shaped like clover leaves; there is a different type for every amino acid. At the bottom of every tRNA molecule
is an anti-codon that binds to the codon on the mRNA strand.

Ribosomes: The ribosome is the active site for protein synthesis. It is made up of protein and RNA molecules. It
can accommodate 2 tRNA at a time.

–
Enzymes: The enzyme that controls the formation of mRNA is RNA polymerase.
The way DNA codes for proteins:

The order in which the bases A, T, G and C are arranged in the DNA molecule forms the genetic code and hence
determine what an organism will look like and how it will function. A set of 3 bases is called a triplet code, or a
codon.

For example, the base sequence AAT|GCC|GGG|CTG|AAA|CGT, are codon codes for an amino acid. Hence this
sequence translates into the amino acids leucine, arginine, proline, aspartic acid, phenylalanine, and alanine.

A protein is made up of one or more chains of polypeptides, and each polypeptide is made up amino acids and
peptide bonds, hence this sequence of amino acids will be part of a protein.

There are 20 different amino acids

However, for every codon, there needs be a set of 3 bases (ie AGC), but there are 4 different bases, so through
the “basic counting principle”, a codon is XXX, in each X there can be 4 base, so the number for every possible
codon is 4 x 4 x 4 = 64.

This means that for one amino acid, there can be more than one triplet code.

For example, TCT, TCC, TCA or TCG on the DNA strand in the nucleus codes for the amino acid “serine”.
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–
Stage One – Transcription (copying of the genetic code from an unzipped DNA molecule onto mRNA):

An enzyme RNA polymerase binds to part of the DNA called the promoter and the double stranded DNA
molecule in the nucleus unwinds a short section so that just the gene in that part is to be used.

The strand coding for the gene exposes itself to the nucleoplasm where the enzyme RNA polymerase moves along
the strand, attaching loose RNA nucleotides to the DNA, with A-U and C-G, until the whole gene is copied.

This new RNA strand is called messenger RNA (mRNA), it acts as a messenger.

A start codon, and a stop codon determine the length of the gene

The mRNA strand exits the nucleus and enters the cytoplasm
–
Stage Two – Translation (Process in which ribosome’s move along mRNA, turning the code into an amino acid
sequence):

The mRNA strand binds to a ribosome in the cytoplasm, the ribosome moves along the mRNA strand, to ‘read’
more of its bases.

As the ribosomes move along the mRNA molecule, they attach tRNA molecules floating in the cytoplasm, these
tRNA have anti-codons complementary to the codons of the mRNA. Eg, if the mRNA had an AAG codon, the
tRNA UUC would bind to it.

tRNA has 2 ends, on one end it has the anti-codon, on the other end tRNA is able to bind with an amino acid
corresponding to the specific anti-codon, for example from above it would have the amino acid for the bases
UUC, NOT AAG.

After the tRNA has produced the required amino acid from the anti codon, it releases its amino acid to attach to
via peptide bonds with the continuation, meaning its moves away from the mRNA, leaving the growing chain of
amino acids.

It then moves back into the cytoplasm where they can pick up other amino acids to be reused. Note: the ribosome
can only accommodate 2 tRNA.
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
The ribosome moves along the mRNA, and more and more amino acids are attached, with peptide bonds, to the
growing polypeptide chain.

When a ‘stop’ codon is reached, the polypeptide chain is released into the cytoplasm, for further processing, to
become a protein.

Explain how mutations in DNA can lead to the generation of new alleles:
–
A mutation is the change in the DNA information on a chromosome.
–
This produces new alleles of genes in species, because if the DNA is changed on a chromosome in a set “locus”, the
DNA structure changes, and hence a new allele, so creates new genetic variation.
–
A mutation in a body cell is called a somatic mutation; it cannot be passed on to offspring.
–
If the mutation occurs in the sex organs, then the mutation will be passed on to offspring.
–
A mutation in the DNA material affects cell activity, because a change in the base sequences alters protein
production.

For example a single mutation in the haemoglobin molecule leads to the production of a different amino acid
(valine instead of glutamic acid) and produces the genetic change.

Discuss evidence for the mutagenic nature of radiation:
–
Mutagens are environmental factors that increase the rate of mutation (change in DNA information).
–
Radiation through many experiments and environment studies has proven itself to be an agent of mutation, it is
known as ionising energy, as it is able to known electrons out of atom orbitals hence turning them into ions, and
decomposing the ‘natural’ state of the atom.

Further effect of radiation on DNA strands:
 E.g. UV light, X-rays, radioactive materials
 Can cause bases to be deleted, totally removed from strand
 This causes a disruption in the normal functions of DNA, the hydrogen bonds can be broken.
 High-energy radiation levels can actually break up the whole chromosome
–
Evidence for the mutagenic nature of radiation:

First generation radiotherapists, who did not now the dangers of radiation, often died young. Scientists are Marie
Curie and her daughter would carry uranium around in their pockets, and developed and died from leukaemia
cancers very quickly.

Hans Muller received the Nobel Prize in 1927 for showing that DNA had the ability to mutate when exposed to
X-rays.

George Beadle and Edward Tatum carried out an experiment to investigate nutritional mutations.

After atomic bombs were dropped on Hiroshima and Nagasaki in WWII in 1945 the after effects were increase in
cancer deaths which correlates to the exposure of the surviving population to high levels of radiation from the
atomic blast. People who live in areas which have been affected by high-level radiation, such as Hiroshima, or
Chernobyl, still show high incidences of cancers and other mutations in their offspring.
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
Explain how an understanding of the source of variation in organisms has
provided support for Darwin’s theory of evolution by natural selection:
–
At the time when Darwin and Wallace proposed their theory of evolution by natural selection, there was no
knowledge of WHAT was responsible for differences in individuals within a population or HOW such
characteristics could be passed from one generation to the next.
–
Through the neo-Darwinian theory of evolution (the explanation of Darwinian evolution based on modern genetics)
the understanding of how genotypes and therefore phenotypes lead to variation in organisms.
–
Variation applies to the differences in the characteristics (appearance or genetic makeup of individuals in a
population
–
Variation comes from:

The random segregation of chromosome pairs during meiosis, and the independent assortment of genes for
characteristics in the production of sex cells.

Crossing over of genetic material during meiosis

Random pairing of sex cells at fertilisation

Mutation of the genetic material

The phenotypes that are variable are “chosen” by the environment
–
Darwin’s theory requires variation, meaning individuals are different from one another and this is present within
organisms. Evolution occurs because natural selection works on the variation in individuals. Selective pressures
determine the individuals that survive and reproduce to pass on their genes and characteristics.
–
Over time, some genotypes hence phenotypes become more prevalent than others.

Describe
the
concept
of
punctuated
equilibrium
in
evolution
and
how
it
differs from the gradual process proposed by Darwin:
–
Darwin’s Gradualism:

Darwin proposed that populations change slowly and gradually (gradualism) over time, ie at a slow constant rate.

However, it is only when the environment changes that natural selection occurs.

The enviroment doesn’t continually change, and this is proved by the fossil record of organisms such as the
dinosaurs, they were present in large numbers, then as the enviroment changed, most dinosaurs became extinct.
–
Punctuated Equilibrium:

In 1972, 2 scientists, Stephen Gould and Niles Eldridge, put forward a theory; they called it punctuated
equilibrium.

The fossil record suggests that organisms remain un-evolved for millions of years, they reach an equilibrium,
however they then evolve suddenly and rapidly, ie this equilibrium becomes punctured by sudden environmental
changes which lead to evolutionary changes.

Punctuated equilibrium proposes that, instead of gradual change, there have been periods of rapid evolution
followed by long periods of stability, or equilibrium.
–
If an environment remains stable for many years, we would expect there to be no change in the organisms living
there.
–
The fossil record in fact shows periods of stability followed by mass extinctions and rapid change.
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
Analyse information to outline evidence that lead to Beadle and Tatum’s ‘one
gene – one protein’ hypothesis and explain why this was changed to ‘one gene
– one polypeptide’ hypothesis:
In the beginning of the 20th century biologists were still not sure of the chemical nature of heredity material, it was
–
debated to be protein or DNA.
–
In 1941 George Beadle and Edward Tatum carried out an experiment to investigate nutritional mutations.
–
The experiment carried out:

They knew that bread mould, a type of fungus (Neurospora crassa), grows in a broth, where sugar, salts and
vitamin are existent. This nutrient base was called the “minimal medium”.

They reasoned that for these nutrients to be used by the fungi, they must be converted into amino acids, and that
enzymes were responsible for this change.

They then exposed the mould to X-rays, to induce mutations (change in genes); this ‘new’ mould was called a
mutant.

This mutant mould was then grown on the minimal medium; if the mould grew it was discarded.

However some moulds didn’t grow, meaning a particular enzyme was no longer functioning to produce an
essential amino acid, it was grown on a different medium, WHICH contains differing amino acids.

–
It was found that if the mould was supplemented with amino acids, it could grow healthily.
Then they theorized “one gene – one enzyme” hypothesis, that is x-rays had destroyed the gene that coded for the
enzyme to make the amino acid.
–
Explanation to why theory this was changed:

The theory was first changed to “one gene – protein”, this is because genes encode for many proteins (example
haemoglobin, hormones and DNA), not just enzymes.

However this was again changed, to ‘one gene – one polypeptide’, this is because genes are not necessarily
responsible for the structure of an entire protein, but for EACH (one) polypeptide chain making that protein, so
many genes are actually needed to make a protein each having different polypeptides.
 Ie not every gene codes for proteins completely (most do), NOT ALL.

Process information to construct a flow chart that shows that changes in DNA
sequences can result in changes in cell activity:
–
If there is a simple substitution for a single base pair on a strand of DNA such as a G-C replaced by A-T, then this
will result in a different amino acid codon forming a different polypeptide. If one base pair is lost from the sequence
there will be a shift along the DNA molecule producing different polypeptides.The flow chart below shows the
reaction if thymine is lost from the start of a DNA sequence.
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
Process and analyse information from secondary sources to explain a modern
example of ‘natural’ selection:
–
Search for better health, where bacteria develop antibiotic resistance.

Process
information
from
secondary
sources
to
describe
and
analyse
the
relative importance and the work of:
–
James Watson
–
Francis Crick
–
Rosalind Franklin
–
Maurice Wilkins
In determining the structure of DNA and the impact of the quality of
collaboration and communications on their scientific research.
–
Discovering the structure of DNA:
–
Scientific discoveries are rarely the work of one person but tend to result from teams of people bringing together
different skills. These teams may be working together or may be scattered all over the world working independently
in different laboratories. The discovery of the DNA is credited to four people: Rosalind Franklin and Maurice
Wilkins from King’s college and James Watson and Francis Crick from Cambridge univeristy.
–
The discovery of the DNA, unlocked a new understanding of the ‘blueprint of life’, that every cell of every living
organism contains DNA, which:

Stores all instructions for biochemical processes in cells

Self-replicates (before cell division).

Is transmitted from one generation to the next in gamtes, accounting for the characteristics of organisms.

Brings about variation, on which Darwianian depends, through mutation (change in DNA) or recombination
(sexual production).
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–
Rosalind Franklin:

In 1938, Rosalind Franklin entered Cambridge University to study chemistry.

Rosalind began researching X-ray crystallography, a method of determining the structure of crystals based on the
use of X-rays. With this technique, the locations of atoms in any crystal can be mapped by looking at the image of
the crystal under an X-ray beam.

In 1951, she moved to King’s College in London to establish an X-ray crystallography unit that would investigate
the structure of DNA. She used a technique called X-ray diffraction that showed that the DNA had all the
characteristics of a helix.

Franklin did not want to announce her findings without sufficient evidence. However, Maurice Wilkins disliked
each other as scientific partners, which lead to Wilkins sharing her results to Watson and Crick without her
knowledge or consent.
–
James Watson and Francis Crick:

In 1953, two postgraduate students, James Watson and Francis Crick began working together at the Cavendish
Laboratory in Cambridge, to find the secret of life, they combined effort and creativity with collaboration in their
approach to research.

They used cutout cardboard shapes to work out the possible chemical bonds between the bases, sugars and
phosphates. They tried fitting the shapes together assuming that the sugars and phosphates are the backbone of the
DNA.

The crystallography studies of British biophysicists Maurice Wilkins and Rosalind Franklin showed that the DNA
molecules consist of two strands joined together, the strands being twisted into a helix with a constant diameter of
about 2 nanometres, and each complete turn of the helix is 3.4 nanometres long.

They realised that if the small purine bases were paired opposite the larger purines this would give a chain of
constant diameter.

Watson and Crick furthermore proposed that adenine always paired with thymine, and guanine with cytosine.
They suggested that when arranged at a certain angle, hydrogen bonds form between the pairs of bases.

They concluded that there were two clockwise spirals of DNA joined together, running in opposite directions- the
double helix.

In 1962 Crick, Watson and Wilkins shared a Nobel Prize for this discovery. Rosalind Franklin had died four years
earlier.
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5. Current reproductive technologies and genetic engineering have the potential
to alter the path of evolution:

Identify how the following current reproductive technologies may alter the
genetic composition of a population:

–
Artificial insemination:
–
Artificial pollination:
–
Cloning:
Discuss the potential impact of the use of reproductive technologies on the
genetic diversity of species using a named plant and animal example that has
been genetically altered:
–
Reproductive technologies include:

Hybridisation (discussed later)

Artificial insemination

Artificial pollination

Cloning

Transgenic species (discussed later)
–
Artificial insemination/pollination are types of selective breeding, in which different organisms are selected to
produce a “likely” organism (this is not guaranteed), cloning involves producing EXACTLY the same organism.
–
Artificial Insemination:

It is the process in which animals are selective breeding without actually mating the two organisms, it is done
through the injection of male semen into a female ova, in a hope of the organism to produce a desirable
characteristic of both parents.

Commonly used with species of large mammals; eg cows, sheep, horses, etc

An example includes crossing a male Friesian cow (known for its size) and female Jeresy cow (known for its
ability to produce large quantities of creamy milk).

ADVANTAGES:
 Can be used to inseminate many females from one male with desirable characteristics.
 Transport of semen is much easier than transporting a whole animal, therefore cost effective and safer.
 Semen can be stored indefinitely, a male can be dead but still produce organisms. It can be used to increase
number of endangered species.

DISADVANTAGES:
 Reduces the genetic diversity found in populations because one bull may be used to sire hundreds or thousands
of offspring , meaning its genes in the population is greater then the normal percentage making them susceptible
to changes in the environment (e.g. new disease)
 Undesirable treats can be brought about, for example the trait being favoured may exceed what is needed and
start damaging the organism itself (such as the cows udder being so large they cannot walk).
–
Artificial Pollination:

It is the process in which pollen (male gamete) from the male anther is collected. It is then dusted onto the female
pistil, stigma (female gamete) of another plant. The pollinated flower is covered to prevent pollination from other
flowers.
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
Plant breeders carry out artificial pollination to breed plants with specific characteristics (like Mendel did).

ADVANTAGES:
 Particularly useful and easy way of breeding new varieties of plants.
 Very simple method involved, hence saves money and time.

DISADVANTAGES:
 The genetic variation is reduced.
 If mass numbers of plants are very similar, one disease can wipe the population out.
–
Cloning:

Cloning is the method of producing genetically identical organisms without the means of sexual reproduction.

It takes out the “unpredictable nature” of artificial insemination/pollination, where ‘trial and error’ breeding is
relied on, until the desired combination is brought about such that it can be further be selected and interbred.

Plant Cloning:
 One of the most commonly used method, and the oldest, is cutting and grafting. A stem of short section of
another plant is cut off, dipped in root-growth hormones, and planted into soil. The plant that grows is a clone
of the original plant
 Tissue culture technology has allowed mass cloning of plants. Firstly, a section of a plant, eg, a root tip, is
pulverised using a blender to release the individual plant cells. The cells are grown on a nutrient medium, and
incubated under controlled conditions.

Animal Cloning:
 Much more difficult than plant cloning, its is hardly done. Discussed below.

ADVANTAGES:
 In agriculture, cloned plants have identical requirements and grow in similar ways to produce similar yields at
the same time.
 In plants and animals identical copies of desirable varieties can be produced

DISADVANTAGES:
 All plants susceptible to the same diseases.
 Cloning is expensive, and with limited advantages over other reproductive techniques.
 Not every clone is ‘perfect’, many problems arise after mass production.
 Cloning of animals has raised ethical questions about the cloning of humans.

Process information from secondary sources to describe a methodology used in
cloning:

The methods use in cloning, are different, however the most common is through “somatic cell nuclear transfer”
(SCNT). Note: somatic cells (also known as body cells) refer to any cell other then sex cells (gametes).

The process of SCNT involves 3 animals, one that donates a nucleus from any of it somatic cells, one female that
donates a egg cell (female gamate) WITHOUT a nucleus, and a third animal that will act as a surrogate (the
female animal that allows an completely unrelated “cell” to be grown in itself till the organism is produced).

Methodology (this method was used to produce Dolly the Sheep):
 From the first adult sheep tissue a mammary cell is removed (it doesn’t matter, as long as it it’s a somatic cell)
from sheep and cultured in lab.
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 From the second sheep (being female) a EGG cell was extracted, and from this the nucleus removed from one
of these cells, this was called an enucleated egg cell (egg cell with genetic info removed).
 Then, from the first sheep the “mammary nucleus” was inserted into the egg cell. Gentle electric pulse causes
nucleus to fuse with egg cell
 A second electric pulse starts cell division, this development leads to the formation of an embryo.
 This new embryo cell is implanted into a surrogate female sheep where it grows into a new organism.

Outline the processes used to produce transgenic species and include examples
of this process and reasons for its use:

Analyse information from secondary sources to identify examples of the use of
transgenic species and use available evidence to debate the ethical issues
arising from the development and use of transgenic species:
–
Transgenic species are organisms which have had some parts of genetic material (genes) from a different species
transferred into their chromosomes. These newly genes are known as trans-genes.
–
The introduced gene instructs the transgenic organism to produce the desired trait or products, his trait may be
passed onto future generations.
–
Note: transgenesis is a form of reproductive technology, similar to cloning.
–
Process used:

Isolating Genes: From an organism known for its “specific/renowned characteristic”, the gene is identified used to
produce that characteristic. Once a useful gene is identified, it has to be isolated by ‘cutting’ it out of its DNA
strand. Special enzymes, called restriction enzymes (also known as gene shears/scissors) are used (more than 800
types are known, each type cut the DNA in a particular place). They cut DNA by breaking the hydrogen bonds
between DNA bases– the ends are called “sticky ends”
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
Making Recombinant DNA: The DNA strands from 2 organisms are cut using the same enzyme, the sticky ends
will match. When they are mixed, the new gene will match and link with the DNA strands (known as annealing),
this new formed DNA is known as recombinant DNA. DNA ligases are also added to strengthen and repair the
bonds.

The replication process: Once recombinant DNA is formed, multiple copies are created through a process called
gene cloning, using polymerase chain reaction (PCR). This polymerase catalyses DNA replication to create
billions of copies very quickly.

Producing Transgenic Species: Once the DNA is created, it is transferred back into the organism through the use
of a vector (a carrier of a substance from one species to another, it can be an organism or human equipment). The
most common method being microinjection, it is when the DNA is transferred into the cell nucleus of another
species using a fine glass needle known as a micro-pipette.
–
Examples of Transgenic Species:

BT Cotton :
 Over the years, traditional pesticides used on cotton plants had to be made stronger and more frequently to
eradicate insect pests such as the Helicoverpa zea moth. The moth is a pest in which destroys hundreds of
millions of dollars worth of cotton each year.
 As more spraying were used, these moth built up immunity to the pesticides due to natural selection of
favourable anti-pesticide characteristics in some moths.
 Bacillus thuringiensis (BT) is a naturally occurring soil bacterium, it codes for the production of a toxic
inactive protein that is harmless to humans and most animals, this gene is transferred to cotton. When the
protein is eaten by the moth, it is converted by the digestive system into an active form of poison that kills the
moth.

Roundup Ready soy beans:
 Roundup is a herbicide (substance used to kill unwanted plants), the organism used to give it this characteristic
is Agrobacterium sp. It is widely used in agriculture with soybeans to be tolerant to roundup. Farmers can spray
crops with herbicide to kill competing weeds without killing soybean crops.

Cold strawberries:
 A gene from a type of salmon that allows it to survive cold temperatures has been isolated, and inserted into a
strain of strawberry. This strawberry can survive and grow in cold temperatures.
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–
Discussion (for the first dotpoint about impact [positive discussed below, negative is fused with ethics which is the
second dotpoint specifically for transgenic species]): (continuation for 'impact of current reproductive technologies')
–
(dot point 1; positives) Further reasons for Using These Processes:

These processes enable scientists to combine the qualities of different organisms

Transgenic species are being developed to:
 Increase the resistance of plants or animals to diseases, pests or extreme environmental conditions
 For medicines and vaccines and to study human diseases
 To improve productivity of crops, pastures and animals
 To improve the quality of food and efficiency of food processing
–
(dotpoint 1 and 2: negatives (more specifically ethical wise)) Ethical Issues of Transgenesis:
–
Ethics is a law philosophy that addresses questions about morality — that is, concepts such as good and evil, right
and wrong.

These technologies help treat diseases and increase food production

Should we be tampering with nature in this way?

Is it right to change living organisms for commercial gain?

Transgenesis disrupts evolutionary relationships between organisms

If a transgenic species was released into the natural environment, it could out-compete the natural organisms

Health-risks and side effects with eating GM foods.
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Biology - Blueprint of life
1. Evidence of evolution suggests that the mechanism of
inheritance, accompanied by selection, allow change over
many generation
Outline the impact on the evolution of plants and animals of: Changes in physical
conditions in the environment, Changes in chemical conditions in the environment and
Competition for resources
Evolution: the change in a species over time
Change in environment is the driving force behind evolution. Environmental change limits
resources, placing selective pressures on organisms. Competition for resources will arise.
‘Survival of the fittest’ occurs- those with favourable characteristics survive and reproduce.
Changes in physical environment (temp, water & light availability, wind):
Changes in Aus physical environment in the past 25 million years, has led to evolution:
 Increased aridity led to decrease in rainforests and increase in grasslands and
woodlands.
 Drying up of lakes led to species that could conserve water e.g. water-holding frog
Changes in chemical environment (gas and salt levels, pH):
 The increasing oxygen levels in the environment when photosynthetic organisms
appeared on Earth, led to aerobic (respiring) organisms.
 DDT resistant mosquitoes
Competition for resources (food, water, nesting sites, mates):
 Competition can occur within or between species
 In Aus, the introduced species (rabbits, cane toads) has caused competition with
native species, leading to the extinction of many species. E.g. the European rabbit
has outcompeted the bilby and Bitou bush has outcompeted Acacia in many areas
Analyse information from secondary sources to prepare a case study to show how an
environmental change can lead to changes in a species
Species: mosquitoes
Environment change: spraying of insecticides such as DDT to kill mosquito cause a chemical
change in the environment
Change within species: increase in frequency of pesticide resistance in the species.
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Result: Most of the mosquito population, who were not resistant to DDT’s, died out. Those
few individuals resistant to DDT’s due to random mutation, survive and pass on favourable
characterises to offspring. This resulted in an increase in frequency of pesticide resistance in
the species= evolution
Describe, using specific examples, how the theory of evolution is supported by the
following areas of study, (1) Palaeontology; including fossils that have been considered to
be transitional forms, (2)Biogeography, (3) Comparative embryology, (4) Comparative
anatomy, (5)Biochemistry.
1. Palaeontology- (study of fossils)
Fossils: any preserved remains or traces of past life preserved in rock, ice, amber, tar, volcanic
ash.
Fossils show the evolution of organisms that originated from a common ancestor, revealed in
transitional fossils. These are the ‘missing links’ between groups - exhibit characteristics of
two different groups of organisms and reveal a successive change in a species over time
Evidence: Archaeopteryx shows a transition between reptile to bird. It has the long-bony tail,
claws and reptilian teeth of a reptile, but a wish-bone, feathers and wings of a bird.
Seed ferns show a transition between ferns (reproduce by spores) and conifers and flowering
plants (reproduce by seed-bearing).
Limitations: Fossil record is incomplete, bias towards organisms with body parts better suited
to fossilising (Lack of soft-bodied/early organism fossils)
2. Biogeography – (study of geographical distribution of organisms)
A new species arises when a group of organisms become isolated from the rest of the
species and are faced with different environmental pressures, supporting evolution from a
common ancestor.
Evidence: Flightless birds - emus in Aus, kiwis in NZ, ostriches in South Africa, and rheas in
South America. This suggests these birds originated from a common ancestor on Gondwana,
and evolved on the isolated continents
Limitations: Limited to studies of species which have become isolated at some point
3. Comparative embryology – (comparing development stages of embryos of different
species)
Similarities in embryonic development suggest a common ancestor.
Evidence: the embryos of different vertebrates are very similar in early stages. E.g. fish,
amphibian, reptile, bird and mammal embryos all show gill slits and tails at some stage
4. Comparative anatomy – (study of similarities and difference in structure of organisms)
Similar structures are evidence that they evolved from a common ancestor
Evidence: Homologous structures are evidence for divergent evolution. These are organs that
have the same basic structure, but with different functions, that have derived from a
common ancestor. E.g. Pentadactyl limb possessed by all vertebrates (wing of bird, forarm of
lizard, flipper of whale, hand of human). E.g. Vascular bundle in flowering plants.
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Some homologous structures have become vestigial structures, remnants of body parts no
longer useful e.g. human appendix
Analogous structures are evidence for convergent evolution. This is the evolution of
structures to serve a common purpose in a common environment, but do NOT share a
common ancestor. E.g. protective spines of Aus echidna and Euro hedgehog to discourage
predation
Limitations: Fossils are incomplete and bias, confusion between analogous and homologous
5. Biochemistry – (study of chemicals in cells)
Organisms that share a common ancestry also share the same basic biochemistry. E.g.
humans and chimpanzees have very similar biochemistry = closely related
Amino acid Sequencing: The amino acid sequence of proteins in species is studied.
Similarities suggest common ancestor. Number of differences suggests the length of time
since they separated
DNA hybridisation: Heat is applied to DNA to separate into 2 single strands. Single strands
from two different species are mixed. Heat is applied again and the higher the temperature
required to separate the bonds between the bases indicates how closely they are related
Advantages: Allows comparisons of organisms where there are no homologous structures,
detailed
Disadvantages: Complex, costly, and can only be performed in high-technology labs
Explain how Darwin/Wallace’s theory of evolution by natural selection and isolation
accounts for divergent and convergent evolution.
The theory of evolution by natural selection was proposed by Darwin and Wallace. It states
that within every species there is variation. More offspring are produced than the
environment can support. Competition for resources. Organisms that possess variations best
suited to the environment (survival of the fittest) will survive and pass on these favourable
adaptations to their offspring. Over time, these increase in the population
Isolation: A new species arises when a group of organisms become isolated from the rest of
the species and are faced with different environmental pressures. Hence, different variations
are beneficial. Natural selection occurs.
Divergent Evolution: Organisms from a common ancestor evolving to become different due
to different environment pressures
E.G. Darwin’s finches on the Galapagos Islands. He found 13 different species. He proposed
that they originated from one population, but were subjected to a variety of selective
pressures around the island. As natural selection occurred, the species evolved into diverse
populations
Convergent Evolution: Distantly related organisms evolving to become more similar due to
similar environmental pressures. Natural selection occurs – similar adaptations
E.g. the fin and flipper in sharks (fish), dolphins (mammals) and penguins (birds)
Use available evidence to analyse, using a named example, how advances in technology
have changed scientific thinking about evolutionary relationships.
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New technologies (e.g. DNA hybridisation, amino acid sequencing) have allowed comparison
of chemicals in organisms, increasing knowledge about the relationships between species.
These have produced evidence to both support and disprove traditional classification
schemes
Change in evolutionary thinking:
These technologies have improved our understanding of human’s relationship to
chimpanzees & gorillas. They have caused a change in the classification of primates.
Before, thought that humans were in a separate family to gorillas and chimpanzees (which
were placed in the family with orang-utans). However, recent developments proved that
gorillas and chimpanzees are more similar to humans (in same family) than with orang-utans.
Humans and chimpanzees have 98% of same DNA sequence.
Analyse information on the historical development of theories of evolution and use
available evidence to assess social and political influences on these developments.
Early 1800s- Lamarck
 The Enlightenment saw great evolution in scientific thinking. However, Christianity
remained a dominant force
 His theory said a change in animals from simple to complex forms
 It challenged religious and social beliefs. Society did not support him
Mid-1800s – Darwin and Wallace
 Evolution by natural selection
 Darwin withheld theory for 25 years, afraid of societal rejection
 Published theory during a time of great societal change- Industrial revolution, Church
power was being questioned. Caused much debate between evolutionists and
creationists
 By 1880, natural selection was widely accepted
 Used to explain industrial revolution- technology and education = selective pressures
Late 1900s – Gould
 Theory of punctuated equilibrium
 Criticised for being out of tune with mainstream evolutionary thinking, differing from
Darwin’s ‘gradualism’
2. Gregor Mendel’s experiments helped advance our
knowledge of the inheritance of characteristics:
Outline the experiments carried out by Gregor Mendel
Mendel studied the genetics of the garden pea plant to investigate the inheritance of
characteristics. Mendel performed only monohybrid crosses - a genetic cross where only one
characteristic is being studied. He examined 7 characteristics of peas, including stem height
(short/tall), seed shape (round/wrinkled) and pod colour (green/yellow).
He began by crossing two pure breeding (homozygous) plants with alternative forms (alleles)
for each trait. E.g. tall with short. Then he crossed their off-spring
Results: He thought offspring would be a blend of traits. However, all F1 offspring resembled
one parent e.g. all tall. He suggested that for each trait, one factor was dominant. In F2, the
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other parent’s traits. E.g. tall:short = 3:1, known as the monohybrid ratio. He states that this
other factor (short) was recessive and masked by the dominant factor.
He developed mathematical ratios, summed up in Mendel’s law of dominance and
segregation
 Characteristics are not blended, but are discrete units
 Each characteristic is determined by a pair of ‘factors’ (genes)
 In a gametes, only one ‘factor’ is present
 During fertilisation, the offspring receives one ‘factor’ from each parent randomly
 One factor is dominant of the other, which is recessive – they DON’T blend
Describe the aspects of the experimental techniques used by Mendel that led to his success
Valid and reliable:
 Studied only one characteristic at a time: changed only one variable and controlled
all others
 Performed a large number of crosses - reliability
Accuracy:
 Tightly controlled fertilisation:
 Removed immature of stamen to stop the prevent self-pollination
 Grew plants in separate green-house to prevent accidental cross-pollination
 Manually transferred pollen from one pure-bred plant to the stigma of the other
used a plant with easily identifiable characteristics
Describe outcomes of monohybrid crosses involving simple dominance using Mendel’s
explanations
 when two pure-breeding parents with contrasting alleles are crossed, they create
monohybrids
 E.g. a homozygous (TT) tall plant crossed with a homozygous (tt) short plant
 F1 = all heterozygous (Tt) exhibiting dominant allele (tall)
 when hybrids are crossed, the ratio of dominant to recessive offspring is 3:1 (called
the monohybrid ratio)
 E.g. two heterozygous (Tt) tall plants are crossed
 F2 = 3 tall plants : 1 short plant
T
t
T
TT
Tt
t
Tt
tt
Distinguish between homozygous and heterozygous genotypes in monohybrid crosses
Homozygous genotypes have the same allele for a characteristic. E.g. TT
Heterozygous (hybrid) genotypes have different alleles. E.g. Tt
Distinguish between the terms allele and gene, using examples
Gene: a section of DNA on a chromosome that contains the genetic code for a particular
characteristic. Individuals have two alleles for each gene E.g. gene for height of plants
Alleles: alternative forms of the same gene, found in identical positions on homologous
chromosomes. E.g. Tall (T) or short (t) are two alleles for plant height.
Explain the relationship between dominant and recessive alleles and phenotypes using
e.gs
Genotype: the genetic make-up of an individual
Phenotype: the expressed characteristics of an organism
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For every characteristic, there are two alleles in the genotype.
 In a heterozygous individual, only one allele is expressed. This is termed the
dominant allele and it determines the phenotype.
 The allele not expressed is termed recessive. It does not affect the phenotype of an
individual
E.g. Pea Plant height in a heterozygous individual- the plant will contain both the dominant
tall allele (T) and the recessive short allele (t) in its genotype. However, only the tall allele will
be expressed in the phenotype.
Outline the reasons why the importance of Mendel’s work was not recognised until
sometime after it was published
 Too progressive- very little was known about genetics. Its significance was possibly
not realised
 Was radically different to accepted belief at the time – that offspring are a blend of
traits
 He only presented his papers to a small group of scientists
 He had no established reputation as a scientist –dismissed by scientific community as
amateur
Process information from secondary sources to describe an example of
hybridisation within a species and explain the purpose of this hybridisation
Hybridization within a species is the breeding of two different breeds of a particular
species. They are used to produce offspring with favourable characteristics.
E.g. The Labradoodle – a cross between a Labrador and a poodle. It was originally
bred in the 1980s, when the Australian Guide Dogs Association set out to create a
guide dog that would be safe for allergy sufferers. Poodles wool-like coat was
thought to be hyperallogenic. Although the program had little success, the
Labradoodle was found to have the pleasant temperament of a Labrador and the
high intelligence of a poodle and it is now one of the most popular crossbreeds.
3. Chromosomal structure provides the key to
inheritance:
Outline the roles of Sutton and Boveri in identifying the importance of chromosomes
Sutton:
 Studied meiosis in cells of grasshoppers, suggesting that:
 During meiosis, chromosomes line up in homologous pairs
 Pairs segregate, so that each gamete receives one chromosome from each
pair
 Fertilisation restores full set of chromosomes
 Concluded that chromosomes were the carriers of Mendel’s hereditary ‘factors’
(genes)
Boveri:
 Studied inheritance patterns in sea urchins, suggesting that:
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
 Egg and sperm each contribute half of the chromosomes to the zygote
 If the nucleus of only one parent is present, then offspring will only show the
characteristics of that parent, however with abnormalities
Concluded that a complete set of chromosomes is necessary for normal development
Describe the chemical nature of chromosomes and genes
Chromosomes consist of 60% protein (histone) and 40% DNA. The DNA is coiled tightly
around the protein core.
Genes are a section of DNA on a chromosome
Identify that DNA is a double-stranded molecule twisted into a helix with each strand
comprised of a sugar-phosphate backbone and attached bases – Adenine (A), thymine (T),
cytosine (C) and guanine (G) – connected to a complementary strand by pairing the bases,
A-T and G-C.
DNA:
 A double-stranded molecule twisted into
a double helix shape
 Each strand is made up of a sequence of
nucleotides
 Each nucleotide is made up of a ‘sugarphosphate backbone’ and a nitrogenous
base
 There are four different bases - adenine,
thymine, guanine, and cytosine
 Adenine pairs with thymine (A-T) and
guanine with cytosine (G-C)
 The bases of complementary strands pair
together, held together by weak
hydrogen bonds
Explain the relationship between the structure and behaviour of chromosomes during
meiosis and the inheritance of genes
During the first stage of meiosis, homologous chromosomes line up and crossing over occurs,
in which they may exchange genes. This behaviour ensures that linked genes on a
chromosome can be inherited independently of each other, increasing variability
Explain the role of gamete formation and sexual reproduction in variability of offspring
Gamete formation:
 Crossing over- homologous chromosomes line up and crossing over occurs, in which they
may exchange genes. This behaviour ensures that linked genes on a chromosome can be
inherited independently of each other, increasing variability
 Random segregation- As chromosome pairs separate and move to opposite ends of the
cell to split into four gametes, genes on different chromosomes sort independently of
each other, resulting in gene combinations in gametes that differ from original parent
Sexual reproduction:
 Random fertilisation- male and female sex cells fuse together randomly during
fertilization.
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Describe the inheritance of sex-linked genes, and alleles that exhibit co-dominance and
explain why these do not produce simple Mendelian results
Co-Dominance: When neither allele is dominant over the other, resulting in both being
expressed in the phenotype. E.g. roan-coloured cattle
 If Shorthorn cattle has the gene for red and
white hairs, both will be expressed= roan
 Does not give the simple Mendelian ratio of 3:1,
because a heterozygous animal has two dominant
alleles, rather than a dominant and a recessive
 It results in the 1:2:1 ratio.








Sex-linked Genes:
 Sex is a genetically determined characteristic,
determined by a pair of chromosomes called the sex chromosomes
Females have two X chromosomes. Males have an X and a Y chromosome
Because the Y is much smaller than the X, some genes are only coded for by the X
these are called sex-linked genes and are inherited with sex traits
Most sex-linked characteristics are recessive:
 E.g. Haemophilia is a recessive allele found only on X
 ‘H’ is the dominant, normal allele; ‘h’ is the recessive, haemophiliac allele.
 Females:
 A normal female’s genotype – XHXH
 A carrier female has the genotype - XHXh
 A haemophiliac female has the genotype – X hXh
 Males:
 A normal male - XHY
 A haemophiliac male - XhY
Males only have to inherit a single gene to have the characteristic
Females may be carriers, but they may possess the normal gene as well, which masks the
effect of the haemophiliac gene
This is why some sex-linked characteristics are much more common in males than
females
Mendel’s experiments did not show sex-specific effects, so sex-linked genes do not
follow Mendelian ratios
Describe the work of Morgan that led to the understanding of sex linkage
Studied the breeding of the fruit fly (drosophila)
He looked at crosses between red-eyed and white-eyed flies and found that the results
couldn’t be accounted for by simple Mendelian ratios.
He hypothesised that the gene for eye colour is carried on the X chromosome, concluding
that it was sex-linked
Explain the relationship between homozygous and heterozygous genotypes and the
resulting phenotypes in examples of co-dominance
 In homozygous genotypes (RR), will simply express the present allele in phenotypes
 In heterozygous organisms (RW), neither allele is dominant over the other, resulting
in both being expressed in the phenotype. E.g. roan-coloured cattle
 E.g. blood groups in humans- 3 alleles (O, A & B). Both A & B alleles present = both
expressed
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Outline the ways in which the environment may affect the expression of a gene
The environment may hinder or enhance the expression of a gene.
• Hydrangeas: the acidity or alkalinity of soil influences flower colour. Acidic soil = blue,
alkaline = pink
• Human growth: human height has a genetic basis, but a lack of nutrients or presence of
toxins (cigarette smoke) can restrict growth
Construct a model that demonstrates meiosis and the
processes of crossing over, segregation of chromosomes
and the production of haploid gametes
4. The structure of DNA can be
changed and such changes may be
reflected in the phenotype of the affected organism:
Describe the process of DNA replication, and explain its significance
DNA replication- the process by which an exact copy of DNA is made, during mitosis and
meiosis
Process:
 Catalysed by the enzyme helicase, the DNA double helix unwinds
 Catalysed by the enzyme DNA polymerase, the weak hydrogen bonds between the
two strands break, allowing DNA to unzip and separate into two strands
 Nucleotides are added alongside both strands opposite their complementary bases,
to create two identical DNA molecules
Significance:
 identical copies of DNA made, so that the daughter cells has the same genetic code
 allows for growth and repair through mitosis
 allows for the formation of gametes through meiosis
Outline, using a simple model, the process by which DNA controls the production of
polypeptides
DNA controls the production of polypeptides which form proteins
1. Catalysed by enzyme RNA polymerase, the DNA unwinds and the weak hydrogen
bonds between the two strands break, allowing DNA to unzip
2. Transcription: a transcription of the sense strand of DNA (contains info for protein
synthesis) occurs, whereby RNA nucleotides are assembled to form a complimentary
strand called an mRNA. The sequence of bases is the same as the non-sense strand,
except T is replaced with U
3. the mRNA moves out of nucleus into cytoplasm
4. Translation: mRNA enters a ribosome. As it moves along ribosome, tRNA molecules
are attached, by temporarily pairing the three bases of tRNA anticodons with the
complimentary codons on mRNA.
5. tRNA brings with it an amino acid which are linked to form a polypeptide chain.
These chains are then spliced off their tRNA carriers, and further processed to form a
protein
6. tRNA moves into cytoplasm to pick up another amino acid. mRNA is broken down
into individual nucleotides for reuse
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Simple model:
Explain the relationship between polypeptides and proteins.
A protein is a complex molecule made up of one or more polypeptide chains, folded into a
particular shape, to suit a specific function.
A polypeptide is made up of amino acids linked by peptide bonds.
Discuss evidence for the mutagenic nature of radiation
•
•
•
In the early 1800s, the harmful effects of radiation were unknown and scientists, such
as Maria Curie, were exposed to large amounts of radiation over long periods of time.
Curie died from Leukaemia due to overexposure to radiation
UV radiation has been recorded to increase the incidence of skin cancers in humans.
Survivors of Hiroshima bombing and the nuclear meltdown at Chernobyl suffered
mutations such as infertility and cancers, as a result of being exposed to high-levels of
radiation
Explain how mutations in DNA can lead to the generation of new alleles.
Mutations are any changes in DNA sequence. This results in changes to the amino acids that
are produced, meaning there is a source of new alleles. To produce changes in alleles, the
mutation must occur in the sex cells of the organism which are then passed on to the next
generation. These changes to the genes result in the production of new proteins. Most
mutations are not harmful and lead to variation, but some will lead to genetic disorders.
Explain a modern example of ‘natural selection’
The Peppered Moth:
• Originally population was mainly composed of lighter moths
• They camouflaged on lichen covered trees to hide from birds
• During Industrial Revolution, trees covered in soot and lichen die off
• Light moths can no longer camouflage, become easier prey. Darker moths can hide
better now
• Population shifts from mainly light to mainly dark.
Explain how an understanding of the source of variation in organisms has provided
support for Darwin’s theory of evolution by natural selection
Darwin’s theory requires variation to be present within an organism. We now know the
source of this variation:
 Mutation of the base sequence of DNA
 The random segregation of chromosome pairs during meiosis
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 Crossing over of genetic material during meiosis
 Random fertilisation of sex cells
These support his theory as they provide the mechanisms for variation on which natural
selection act.
Describe the concept of punctuated equilibrium in evolution and how it differs from the
gradual process proposed by Darwin
Darwin’s Gradualism:
 He proposed that populations change gradually over a long period of time
 He used transitional fossils to support this
Punctuated Equilibrium:
 Put forward by Gould and Eldridge
 That evolution occurs in short bursts of rapid change, followed by long periods of
stability
 The fossil record shows millions of years passing without any notable change, and
then evolve suddenly (e.g. soft-bodied organisms dominated the seas for hundreds
of millions of years, and then, in the space of a few million years, they disappeared)
Analyse information to outline evidence that lead to Beadle and Tatum’s ‘one gene – one
protein’ hypothesis and explain why this was changed to ‘one gene – one polypeptide’
Beadle and Tatum
 They subjected the spores of bread mould to X-rays in order to cause mutations and
found that some of the mutated spores could not grow on the nutrient base of bread
unless they added a specific amino acid ‘arginine’
 They hypothesised that the X-rays had destroyed the gene that coded for the protein
arginine calling this the ‘one gene – one protein’ hypothesis
This was later changed to ‘one gene – one polypeptide’, because many proteins are made up
of more than one polypeptide, and a gene only codes for one polypeptide.
Process information from secondary sources to describe and analyse the relative
importance of the work of James Watson, Francis Crick, Rosalind Franklin and Maurice
Wilkins in determining the structure of DNA and the impact of the quality of collaboration
and communication on their scientific research
Scientist
Franklin
Wilkins
Watson
Crick
Role
Used X-ray crystallography to discover that the shape of the DNA molecule was
a helix
Studied the structure of large molecules. Informed Watson and Crick of
Franklin’s discoveries
Worked with Crick to model the structure of the DNA molecule. Suggested that
pairing of bases made it possible to copy and pass on genetic information
Worked with Watson to model the structure of the DNA molecule. Studied the
genetic code.
Franklin was a woman working in a predominantly male field. Before publishing her work,
she wished to gather more evidence but Wilkins showed her results to Watson and Crick
without her permission. This information was enough for Watson and Crick to develop their
model of the double helix structure of DNA.
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Watson and Crick worked well together. They published their findings with each other.
Franklin died of cancer in 1958. 4 years later the other three were awarded the Nobel Prize.
The accepted model of the structure of DNA is usually known as the Watson-Crick model:
there is no mention of Franklin.
5. Current reproductive technologies and genetic
engineering have the potential to alter the path of
evolution
Identify how the following current reproductive techniques may alter the genetic
composition of a population: artificial insemination, artificial pollination, cloning
Reproductive technologies are used for selective breeding to produce hybrid offspring with
particular desirable characteristics. All reduce genetic variability.
Artificial pollination: pollen from the stamens of one plant is dusted onto the stigma of the
same or different plant. E.g. Mendel used this technique in his experiments with pea plants
Artificial insemination: sperm is taken from a chosen male and artificially introduced into
several selected females. E.g. in livestock, used to produce desirable characteristics- crossing
a male Friesian (produce large quantities of milk) with female jersey cows (produce creamy
milk) to create offspring who produce large amounts of creamy milk.
Artificial pollination and insemination alter the genetic composition of a population:
 Individuals with traits considered by the breeder to be advantageous are selectively
bred to produce ‘ideal’ hybrid offspring with new combinations of alleles.
 Allows humans to manipulate combinations of alleles and therefore increase the
frequency of those considered advantageous by the breeder, rather than alleles that
increase their fitness in the environment
Reproductive cloning: is the production of an individual genetically identical to one parent
1. Cloning of ‘ideal’ hybrids (e.g. seedless grapes) is a form of selective breeding
Process information from secondary sources to describe a methodology used in cloning
Somatic cell nuclear transfer (SCNT) is a cloning methodology. It was used to create Dolly the
Sheep. It involves 3 animals:
1. Udder cells taken from sheep 1 and starved of nutrients to stop them dividing
2. Nucleus of unfertilised egg taken from sheep 2 removed by enucleation
3. Udder cell from sheep 1 injected into enucleated egg of sheep 2. Electric current
applied to fuse the two cells.
4. The embryo began to grow in virto. It was implanted into uterus of sheep 3, where it
continued to grow. After pregnancy, a lamb was born genetically identically to sheep
1
Outline the process to produce transgenic species and include examples of this process and
reasons for its use
Transgenic organism- one whose normal genome has been altered by introducing a gene
from another species into it in a process called genetic engineering.
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Reasons: creating foods with increased nutrients and higher yields. Introducing resistance in
species to disease, pests and pesticides
Process: ‘cut, copy and paste’
1. ‘cut’- a gene for a favourable characteristic is removed from the cell of an organism,
using restriction enzymes
2. ‘copy’- gene cloning occurs, whereby multiple copies of gene is made, usually carried
out in bacteria
3. ‘paste’- the genes are inserted into an egg cell of another species and after
fertilisation becomes part of the newly formed organism’s DNA
4. The egg develops into a mature organism with the new gene ‘switched on’ to
function
Four main ways of ‘pasting’:
1. Micro-injection of DNA into single cell
2. Biolistics- Using a gene ‘gun’ to ‘fire’ DNA on particles into target cells
3. Electroporation- applying electric current to target cells to increase membrane
permeability, allowing new genes to be inserted
4. Transduction by a vector
Example: Bt cotton
Reasons:
 Pests such as the caterpillar of the Helicoverpa zea moth destroy millions of dollars
worth of cotton each year. The Bt gene codes for the production of a toxic protein
that is harmless to humans and most animals, but deadly to caterpillars.
 This reduces the need to use pesticides – better for environment, reduces the
development of pesticide resistance
 Increases cotton yield
Process:
1. ‘cut’- Bt gene is removed from the bacterium Bacillius thuringienis, using restriction
enzymes
2. ‘copy’
3. ‘paste’- the genes are inserted into cotton plant embryos through transduction by a
vector
Analyse information from secondary sources to identify examples of the use of transgenic
species and use available evidence to debate ethical issues arising from the development
and use of transgenic species
Examples:
 Salmon gene inserted into strawberries in Scandinavia so they can grow in cold
temperatures
 Spider genes inserted into goats so that they secrete tiny silk strands used to create
sutures and uniforms that are light and strong
 Human insulin gene inserted into fish in Belgium, used to treat diabetics
Ethical issues:
Ethical issue
Arguments for
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Arguments against
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Environmental
issues
 Reduces use of pesticides
 Loss of biodiversity
 Potential for escape of the
Financial &
social justice
issues
 Increases production of food for growing
Health issues





Human rights
issues

human population
Higher yield at lower cost
Less spoilage of produce during
transportation
Foods with higher nutritional value can be
developed
Reduces use of pesticides
Plants can produce vaccines to improve
human health
GM crops may be used to solve food
shortages in third-world countries,
producing a higher yield at lower cost
transgenes into other
populations
 Speeds up genetic change in a
species
 Is it ethical for single
companies to have the rights
to these technologies while
others don’t, creating a
monopoly
 Safety of GM foods unknown
especially for people with
allergies
 Vegetarians may unknowingly
eat food with animal genes
 If a human gene is inserted
into an animal, are we
humanising it? Is it acceptable
to eat the meat of an animal
that contains human genes?
Discuss the potential impact of the use of reproductive technologies on genetic diversity of
species using a named plant and animal example that have been genetically altered
Reproductive technologies often lead to a decrease in biodiversity, as large numbers of
identical organisms are produced and bred (e.g. through cloning) or if organisms are
selectively in-bred to maintain parent lines of hybrids that benefit us in terms of agriculture
produce. A lack of variation is a major risk factor in extinction of a species, as they are less
likely to survive sudden environmental change or would be vulnerable to pathogens.
Genetically modified plants:
E.g. Bt cotton is rapidly replacing other varieties of cotton in commercial agriculture.
Disadvantages:
 Many natural varieties of cotton will be lost
 Having a monoculture means that the crop becomes more susceptible to
environmental change and may also lead to Bt resistance in insects
Genetically modified animals:
Some salmon have been genetically modified so that they grow bigger than normal salmon.
Female salmon are attracted to and mate more often with larger males. If the transgenic
salmon were to be released in the wild population then wild females would mate with the
larger transgenic males. This transgene would rapidly spread in the natural population,
reducing diversity.
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Blueprint of Life – Bio Notes
Outcome 1 – LEFT HAND SIDE
Outline the impact on the evolution of plants and animals of:
Changes in physical conditions in the environment:
 Peppermoths:
o There was a diversity in the colour of the peppermoths,
black, white and speckled
o With the Industrial Revolution came soot which
covered the trees, providing an environment more
favourable to the dark peppermoths, able to hide from
prey
o Dark feature became more frequent in the population
over time because the light peppermoths were predated
before they could pass on their genes
o As the Environment was progressively cleaned, so too
did the light feature become more frequent within the
population
 Temperature Clines:
o There is a gradient in the sizes of a species across
different climatic regions
o Larger animals are generally found in the colder areas
due to their ability to retain heat and remain insulated
o Smaller animals are generally found in the warmer areas
due to their ability to lose heat
o E.g Kangaroos in Tasmania vs QLD, Wombats, possums
OR Snowy gums (larger plants in warmer areas)
 Effect of Fire:
o Aussie Schlerophyll plants (e.g. eucalyptus and banksias)
have seeds that can only germinate after a bush fire
causes the seed to open
o They also have lignotubers which after a fire are
stimulated to sprout from the deeper layers of the
trunk and roots (previously protected by outer layers)
forming shoots
o Rainforest plants lacked these features and therefore
died out when the environment started to change
Changes in chemical conditions in the environment:
 Bacteria developing resistance to antibiotic chemical:
o Golden Staph bacteria have, over time, become
resistant to most antibiotics
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WA possums resistant to poison fluoroacetate
o Trees in WA have fluoroacetate in them, progressively
killing off all those possums without the resistant gene
o Trees on the eastern seaboard do not have
fluoroacetate in them therefore the possums on the
eastern seaboard are not resistant
 Insecticide and mosquitos
Biological Selection Pressures
 Rabbits and Myxoma virus
o Introduced in 1950 and eliminated 99% of rabbits
o By 1960, effectiveness was reduced to 50%
o In +/- 2000, Calici virus was introduced some success
with juveniles, but in the long term the same
reformation of population
o Need to use multiple weapons
 Cichlid Fish
o Different feeding methods:
o Some crush snails
o Others suck eggs out of the mouths of brooding
mothers
o Others eat algae
o Shortage of food increased diversification into
different species
 Flycatchers
o Both leaden and restless flycatcher feed on similar
insects but they feed on them in different ways
o Leaden flycatcher: catches flying insects or collect
insects from trees
o Restless flycatcher: hovers above the ground and emits
a call that disturbs insects – then pouncing on the
insect before taking it to a perch to feed on it
o This is due to competition for food, then leading to a
diversification within the species

Describe, using specific examples, how the theory of evolution is
supported by the following areas of study:
Paleontology (incl. transitional fossils)
 Paleontology works both quantitatively and qualitatively
 Looks at structure/form of fossils, finding possible relations
 Describes chronology through multiple methods of dating
o Carbon-dating for more recent fossils
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
o Radio-metric dating (uranium dating) for rocks
Types of fossils:
o Cast/mold
o Trace, imprint, trails
o Body fossils
o Coprolites
o Amber fossils
Plants
Algae
500 mill ya
Seedferns
400 mill ya
Gymnosperms 300 mill ya
Angiosperms
185 mill ya
Animals
Jawless fish
Bony Fish
Amphibians
Reptiles
Birds
Mammals
500 mill ya
400 mill ya
360 mill ya
300 mil ya
190 mill ya
150 mill ya
 Evidence of earlier simpler forms were followed by more
complex forms – suggesting that each group developed from
the predecessor that was less complex
 Thus common ancestry can be traced back through a series of
dated fossils which become increasingly complex over time –
they can better exploit their environment
 Ancestral fossils: older forms of modern animals showing
progressive changes over time
Horse’s changes over time:
 Increased height – to see over grasses and longer stride to
escape predators and extending their range
 Elongation of limb with middle digit becoming dominant –
allowing for greater stride
 Lower jaw increased in size in relation to upper jaw – heavier
muscles for chewing grass
 Larger teeth
 The changes correlate with change in environment from
rainforest to dry savannah
Transitional Fossils
 Showing structural features of 2 different groups
 E.g. archeoptryx, lobe-finned fish, therapsid – showing feature
of reptiles and mammal, fish and amphibian, reptiles and
mammals
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Biogeographical:
 Geographic distribution of organisms
 Range of species: portion of earth where the species is found
 Interbreeding: does occur throughout the range of a population
 mixing the gene pool  single species will not diversify
o As range increases some individuals are moved further
apart from each other – reproductive isolation
o Sometimes barriers can stop interbreeding
o Physical: e.g. continental drift, water, mountains
o Environmental: salt/fresh water
o Biological: predators, presence of chemicals
  Different natural selection pressures
  Diversification occurs because of reproduction isolation
barriers
Historical evidence
 Gondwanaland continents: Africa, Australia and South
America
o In the beginning: marsupials bred across the range of
Gondwanaland
o As Gondwanaland separated into different continents
 different environmental pressures in different
continents
o Evolution of species into new species etc
 Australia and South America both have modern marsupials
which are descendants of the original marsupial Gondwanaland
ancestor
 Africa does not have marsupials – they were eaten by the big cts
as they evolved in Africa
Modern Evidence
 Ratities – living species (flightless bird)
o Found in Southern Hemisphere
o E.g. kiwi (NZ), Emu (Aus), Ostrich (Africa), Rhea
(South America)
Comparative Embryology
 Early embryos of mammals represent resemble embryos of lower
embryo forms
o Because similar features  similar genes  common
ancestor
 Genes for later embryo development are controlled by genes 
more recently mutated genes dictate diversification
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 Although early vertebrate embryos are simlair, later
development is governed by newer genes which control
development of new characteristics for survival in
new/different environment
Comparative Anatomy – Homologous structures
 Homologous structures: Those in different animal groups that
share basic structural similarity because they are governed by
similar genes
 e.g. the vertebrate forelimb – pentadactyl limb
o Similar muscles, blood vessels, nerves and bone
arrangement
o Ancestors would have moved into different
environments allowing for natural selection and
diversification
o Have come about by divergent evolution
 Vestigial Organs: Structures present which have
o A) Become diminished in size over the course of
evolution because it provided no evolutionary
advantage e.g. appendix or coccyx
o B) Can also be structures that are used quite
differently in the modern animal from those of other
species e.g. middle ear bones – ear bones in humans and
apart of jaw bones in fish
Convergent and Divergent Evolution
 Analogous structures: those in different groups of animals that
have a functional similarity but not related by common ancestry
(no genetic similarity)
 Homologous structures: In different animal groups that share
basic structural similarity because they are governed by similar
genes
Biochemistry
 The basic biochemistry of organisms cannot be ignored
(similarity)
o Membrane of lipoprotein
o DNA/RNA/Both
o Rely on enzymes to control metabolism
o Respiration to release energy for metabolism
o All have similar organic compounds (proteins, carbs,
lipids)
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 So we could classify organisms on the chemical characteristics
instead of only using structural features of the animals and
embryos
 Proteins are made up of amino acids placed in a specific order
dictated by DNA. This can be used to judge the relatedness of
different organisms
 We compare amino acid sequences e.g. blood Hb
 Only one difference in DNA nucleotide sequence is needed to
produce this protein in Gorillas and humans
 No differences in the N-base sequences for this gene between
chimps and humans
Cytochrome C
 Protein necessary for respiration present in a wide range of
organisms incl. bacteria and many plant species
 By looking at DNA sequence or genes which produce this
chemical in difference organisms, we can see how related they
are
 Between humans/apes = 1 difference
 Between humans/bread mould = 63 differences
 Human/tuna fish = 21 differences
Explain how Darwin/Wallace’s theory of evolution by natural selection
and isolation account for divergent evolution and convergent
evolution
 Their theory in 5 points:
o Variation exists among the embers of a population
o Over population more individuals are produced than
can survive – Competition
 Struggle against natural environment – natural
selection factors of environment
o Those organisms with features more suited to the
environment will survive
o Those without the feature will die, removing their
genes from the gene pool
o Over time favoured genes occur with greater
frequency within the population
 Darwin’s terminology: ‘Preservation of favoured races’
 Natural selection is the mechanism by which evolution occurs
 It occurs when environment conditions are changing
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





o Currently rapid evolution is happening due to climate
change
Punctuated equilibrium: Inconstant evolution
D/W never:
o Refer to the first form of life
o Explain the origin of the variation
o Explain how genes transfer from generation to
generation i.e. DNA and genes
Darwin emphasized competition between species
Wallace emphasized more natural selection and pressure effect
Convergent Evolution: Response to similar selection pressures
o When analogous structures become more similar over
time
Divergent Evolution: Response to different selection pressures
o Homologous structures becoming more different over
time
RIGHT HAND SIDE
SEE ‘BIO NATURAL SELECTION PRAC’
Analyse information from secondary sources to prepare a case study
to show how an environmental change can lead to changes in a species
Tiktaalik
 The transitional fossil between a four-footed land reptile and
lob-fin fish
Reptilian Features
Fish Features
Mobile Neck
Fines with some bones like
lobe- fin fish
No bony covering of gills
No fingers and toes
Can flex elbow and extend
wrist
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Observe, analyse and compare the structure of a range or vertebrate
forelimbs
Analyse how advances in technology have changed scientific thinking
about evolutionary relationships




Initially Chimpanzee was considered to be in a separate group to
humans because it was more like other primates than humans
Development in technologies such as DNA hybridization and
Biochemical analysis showed that genetics of human and chimp
were over 99% alike
This evidence provides suitable cause for them to be placed
into the same group, the ‘homo’ group
DNA Hybridisation:
o DNA strands are heated to unwind the double helixes
o 2 strands from different animals are cooled to wind
together
-Hydrogen bonds form between the two single strands
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o Bonded sections rewind to form double helix
o Greater number of hydrogen bonds between strands =
greater degree of genetic similarity
 Biochemical Analysis
o Human serum is injected into another animal e.g. rabbit
o Rabbit’s immune system produces antibodies to these
human proteins
o A serum can be prepared from the rabbit’s blood and
used in tests with the serum of other mammals
o The amount of precipitation that occurs when the serum
of two mammals is mixed together is a measure of the
difference in some of their proteins – an indirect measure
of the relationship between them
o The greater the precipitation the close the relationship
o Another type compare amino acid sequences
o Hb has 4 amino acid chain, one of the chains, containing
164 amino acids is identical for humans and chimps with
one difference between humans and gorillas
Analyse information from secondary sources on the historical
development of theories of evolution and use available evidence to
assess social and political influences on these developments
 Aristotle
o Metaphysical – not scientific
o He believed nature strived to become more complex
and perfect
 Judeo-Christian idea
o Animals were created how they are – there is a fixed
nature of the creatures on earth
th
 16 Century reformation
o religious and political movement against the Catholic
Church – diminishing it’s power
 Renaissance
o Re-learning from the ancient Greeks and Aristotle
o Fossils found
o Leonardo DaVinci – correctly interpreted that fossils
were the remains of animals and those that are
different had become extinct
 Catastrophism
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o In order to explain difference in fossils
o After a ‘catastrophe’ e.g. the flood and Noah’s ark,
there was a new creation – replacing organisms
preceding it
 French Revolution
 Buffon – rejected the theory of special creation
o He believed that small variations produced by the
environment can accumulate so that simple organisms
can become more complex
o Species could change by new ones were not created
o New organisms arose by spontaneous generation
o Condition at the time of spontaneous generation were
governed the types of species that evolved
 Gene Lemarck
o Believed that living organisms have an internal force
controlling development and functioning of their parts
and also enables them to overcome hardships
o Organisms change when the need arises in response to
some sort of demand by the environment
o Theory of use or disuse:
o Those feature we use become bigger and stronger and
vice versa
o Essence is that any trait acquired during the lifetime
will be passed on to future generations
o Weakness: no extinction – organisms had a force
allowing them to constantly adapt
o Over time marked changes could occur in form or
function
o According to Lemarck: short-necked giraffes
stretched their necks to reach higher leaves acquiring
longer necks
o Would then pas on the acquired elongated neck to the
next generation
o Strengths:
o Logical in light of their knowledge
o Explained trends in fossils becoming different over
time
o Explained similarities between parents and offspring
o Confirming the fact that there were environmental
pressures impacting survival & appearance or organisms
o Weaknesses:
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o Do not inherit acquired characteristics
o Doesn’t explain fossils of extinct organisms
 Erasmus Darwin (1731-1802)
o Darwin’s grandfather
o Argued life could have a single common ancestor
although he could not understand the mechanism of
the proceeding descent of species
o Also believed in Lemarck’s idea of acquiring and
passing on characteristics throughout the lifetime of
an offspring
 Charles Darwin mid 1800’s
o Studied medicine and theology in uni – scientific
training as well as creation knowledge
o Made friends with people who recommended him as a
naturalist on board the shop called the ‘beagle’
o Made a 5 year voyage to make maps for the navy
o England at the time was expanding colonies and
becoming a mega world power – leading reason for the
beagle
o 1851 – East coast of South America and by Galopogas
Islands, Pacific, Hawaii, Aus and NZ
o Studied organisms and geology
o Saw similarities and differences between living
organisms on Galapagos Islands and Mainland of South
American
o Saw trends in fossils – simple to complex
o Variation in beaks of the Finch’s so many common
features
o Speciation: new species arising from a common
ancestor through divergent evolution a.k.a adaptive
radiation
o Accumulated evidence from molluscs, birds, corals 
reliability
o Read an essay by Malthys  social commentary on poor
people in England:
o Said that: The population will grow in size until it is
stopped by limited food
o Triggered recollections for Darwin
o A limiting factor/natural selection pressure
o 1844: wrote a summary of his work
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 Wallace: at the same time was working in Malaysia and found
the exact same theory
 Darwin and Wallace: Co-presented a paper
 1859: Darwin’s book was published
Outcome 2
Outline the experiments carried out by Gregor Mendel
 Obtained true-breeding parents by self-pollinating over many
generations
o Assumed they were true-breeding if they always produced
offspring like themselves
 Cross-pollinated true-breeding parents of opposing
characteristics by hand using a paintbrush e.g. tall x short
 Isolated flower from casual pollination from surround
environment by placing a paper bag over it
 Pulled out stamens to prevent self-pollination
 When all came out tall he concluded that tallness was a
dominant factor and was masking the shortness
 Luck: peas are self-pollinating plants
-in pea plants, each characteristic is determined by a single pair
of genes, not multiple pairs of alleles
-independent genes for different characteristics are located on
separate chromosomes in the pea plant
Experimental techiniques
 He controlled all variables by cross-pollinating by hand
 Isolated plants
 Started with true-breeding plants
 Repeated his experiments many times and kept records of
thousands of pea offspring
Summary of Mendel’s work - Analysis
 Identified heredity units – factors/genes
 Identified that for each factor, there are alternate forms called
alleles  opposing characteristics
o In any individual they occur in pairs
 Established that there were dominant and recessive factors
 Each factor is inherited independently, they do not blend
 Law of dominance:
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o Tells us there is no blending of genes, they remain as
separate units, there for in the heterozygous F1, the
dominant allele will always mask the recessive
Law of Segregation:
o Mendel figured that, given the phenotypes of his f1, his f1
must be heterozygote  each generation cannot possibly
have double the genes of the last  there must be half
from each parent, and therefore the parents factors
would have had to segregate and then join up again with
the factors of the other parent
o The pair of alleles will segregate and go to opposite
gametes
o They are haploid
o Half the gametes carry info of one gene and half carry
info of the other gene
o Fertilisation will allow homologous pairs to match again =
diploid
Law of independent Assortment:
o The chromosomes arrange themselves in pairs at the
equator in meiosis one, independently for each meiotic
division
o Number of diff gametes is increased because of this
independent/random assortment
Outcomes of monohybrid crosses involving simple dominance using
Mendel’s explanations
1. A homozygous plant with yellow seeds is crossed with a
homozygous plant with green seeds – P1
2. They produce only yellow offspring because there is a yellow
dominant gene in all – F1
Phenotype = all yellow
Genotype = all heterozygous
3. Self-pollinated P2 (mature F1) to see if the green gene would
reappear and to avoid any outside contamination
4. F2 =
Phenotype = Yellow : Green – 3:1
Genotype = homozygous yellow : heterozygous yellow :
homozygous green – 1:2:1
Homozygous: a pair of alleles with the same feature
Heterozygous: a pair of alleles with different features
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Alleles: two or more genes that occupy the same relative locus on
homologous chromosomes AND produce different effects on the
same developmental process
Dominant gene: is always expressed in the phenotype, even in the
genotype is a heterozygous alleles, it masks the recessive gene unless
no dominant gene is present, in which case the recessive will be
expressed
Why was Mendel's work not recognized until sometime after it was
published?
 Mendel’s work was groundbreaking – 1866
 Little was known at the time about the cell and mitosis and
meiosis were not known
 Wasn’t recognized because Charles Darwin published his work
around the same time period – 1859
 Within 10 years, these principles became firmly established, they
became the principle laws of inheritance
 They were following divergent evolution of Darwin, but
Mendel’s work was inheritance within a species
 Mendel’s work was radically different because he used maths
 People were also confused by his presentation because he was
not a professor, he was rather a monk
Right Hand Side
How to construct a pedigree
 Pedigree: graphic representation of inheritance patterns in a
family
 Importance: used to study the inheritance of certain features
and allows predictions of probability of occurrence of heredity
disorders to be made
 Rules of constructing a pedigree:
o Each gen is represented by a roman numeral on the LHS
o Individual are identified by gen and order of birth
o O = Female
o [_]= Male
o Shaded symbols indicate affected individual
o Horizontal bar joins M+F who produce children
o Vertical line from horizontal bar indicated children born
in order of their birth
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Hybridisation within a species
 Hybrid: the offspring of a cross between two different species,
sub-species or varieties
 Example within a species: corn production in the 1930’s
o Production was increased by interbreeding two strains of
corn, one strain was hardy whilst the other produced
large fruit
o As a result the offspring was hardy and produced large
fruit
 Purpose of hybridization:
o Hybrids are often described as having hybrid vigour – they
combine the best features of parental organisms
o Hybrids (plants) may have bigger flower and withstand
harsher conditions, hybrids (animals) may be stronger and
have a more optimum range of features e.g. the mule
(female donkey x male horse)
Outcome 3
Roles of Sutton and Boveri in identifying the importance of
chromosomes
 Sutton
o Worked with grasshoppers, looking at meiosis occurring in
testes
o Saw chromosomes line up in pair and segregate
o He noticed the chromosome pair was restored at
fertilisation
o Saw the ‘separation of factors’ that Mendel referred to
o Suggested that Mendel’s ‘factors’ are present on the
chromosomes
o Suggested random assortment is responsible for genes of
the next generation
 Boveri
o Worked with sea urchins, watching mitosis
o Showed that chromosomes were passed from one
generation of cells to the next
o Said that chromosomes are the means of inheritance
o Noticed that there are far more inherited factors than
chromosomes  each chromosome must carry multiple
factors
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o Then said that chromosomes can exchange factors
between a pair i.e. crossing over
Describe the chemical nature of chromosomes and genes
 Chromosome  DNA wrapped around a histone protein
 DNA  series of lengths of genes
 Histone protein: blob formation of polypeptide chains acting as
the back bone of the chromosome
 DNA  2 phosphate-lipid strands in opposite directions with
nitrogen bases along the inside of each, each corresponding to
its partner (A-T, C-G) connected by hydrogen bonds
 Gene  a length of DNA
DNA structure
DNA is a double-stranded molecule twisted into a helix with each
strand comprised of a sugar-phosphate backbone and attached bases
– adenine (A), thymine (T), Cytosine (C) and guanine (G) – connected to
a complementary strand by pairing the bases A-T and G-C
Relationship between the structure and behaviour of chromosomes
during Meiosis and the inheritance of genes
 Meiosis has 2 cell divisions resulting in 4 gametes, each with the
haploid number of chromosomes
 Gene pairs are separated RANDOMLY  each gamete only
contains one allele for each characteristic
 Crossing over can occur in the first stage of meiosis -adjacent
chromatids twist around each other, spilt where they touch,
and join up with different pieces  linked genes are separated
and rejoined to form new combinations
 The haploid cell from each parent fusing with another haploid
cells from an entirely different individual with an entirely
different array of genes also determines the inheritance of
genes
Role of gamete formation and sexual reproduction in variability of
offspring
 This random assortment + crossing over, and the combination of
haploid cells derived from very different individuals results in
the formation of totally unique gametes, different from each
other and different from their parent
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 This increases variation in a species because it relies entirely on
chance as to which sperm will fertilize which egg
 Also the same type of egg and sperm being united again is
extremely rare and almost impossible
Describe the inheritance of sex-linked genes and why these do not
produce simple Mendelian ratios
 Sex-linked genes are genes that are carried on the X
chromosome
 This means that males will express every sex-linked gene they
receive, whether recessive or dominant, as they have no means
of masking it on the Y chromosome
 Females on the other hand will only express these genes if a) it is
a dominant gene or b) both of her X chromosomes carry that
same recessive gene (which is rare)
 This will naturally create a bias amongst the sex of a population,
where as Mendelian ratios do not have any sex-bias
 In a typical F2 expressing Mendelian ratios, the phenotype would
be 3:1 (dom:rec) and the genotype 1:2:1 (homo dom:hetero:homo
rec)
 In one example of a sex-linked F2, say the P1 had a normal female
and a colour-blind male (recessive gene), the F2 would have a
phenotype of 3:1 (norm:CB) but only males would be colourblind, with a genotype of 1:2:1 (carrier:norm:affected)
 Although superficially these express Mendelian ratios, only the
males are affected which is not typical of Mendelian ratios
 And when testing dominant sex-linked genes the ratios will
differ again, with a different gender bias in the generations.
Describe the inheritance of alleles that exhibit co-dominance and
explain why these do not produce simple Mendelian ratios
 Sometimes the Mendelians patterns of recessive and dominant
alleles do not apply, this is because two or more of the alleles
are co-dominant
 E.g. in human blood groups there are 3 alleles, o, A and B. A and
B are co-dominant, and o is recessive
o In Mendelian ratios there are as many possible phenotypes
as there are alleles, which would mean in the case of
blood group there would be 3
o Because there are 2 co-dominant genes, it brings about a
4th phenotype ‘AB’
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 When a person has 2 co-dominant alleles for a certain feature,
both alleles are fully and equally expressed, therefore creating
the blood group ‘AB’ rather than just A or just B
Describe the work of Morgan that led to the understanding of sex
linkage
 Morgan, an American geneticist in the early 1900’s tried to
replicate Morgan’s work using the Drosophila fruit fly
 He noticed that some had white eyes and some had red but far
fewer had white than red, so the results he expected were that
the white eye would be the recessive gene and the red eye
would be the dominant but he did not get the results he
expected
 RED FEMALE X WHITE MALE = all red-eyed
 His F2 generation produced a 3:1 phenotype but all the white
eyed flies were males which held a 2:1 ratio of red male to white
male and all females were red-eyed
 He noticed this sex-bias and did a test cross or a back-cross
o Entails the mating of an original white-eyed male parent
with a red-eyed female from
the F1 gen (heterozygote)
 The test-cross resulted in the phenotype of half males AND
half females being white-eyed and vice versa
 He concluded that seeing as females only showed the gene after
crossing a heterozygote female with an affected male: that it
was related to gender (sex-linked)
o That this gene was carried on the X chromosome 
affecting females less because females had a second X to
mask the affected X
o He also proposed that the Y chromosome holds no
corresponding allele
Co-dominance results in phenotypes
 Co-dominant genes are fully and equally expressed in a
heterozygous situation e.g. pink phenotype in a heterozygote
flower where both white and red are dominant
 There is no masking of either allele
 A new phenotype is created in order to express both features
 The autosomal phenotype ratio would be 1:2:1, homo 1 :hetero:
homo 2
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Outline ways in which the environment may affect the expression of a
gene in an individual
 Environmental conditions can prevent genes from being fully
expressed or revealed in a phenotype
 These environmental factors can include:
o Dietary conditions e.g. malnourishment, over-eating –
could effect height, muscle development and bone
development
o Socio-economic background e.g. greater financial ability
provides greater educational, medical, nutritional
resources
o Traumatic life events e.g. accidents or death can affect
mental capacity or working
o Temperature e.g. a gene in the Siamese cat is activated by
the cold and will turn affected area dark brown as
opposed to the beige colour of the rest of the body –
hence it’s dark brown extremities (limbs, ears, tail)
 Even identical twins can differ phenotypically, even their
position in the womb changes their weight at birth and every
slight difference in their lives affect their phenotype
differently, e.g. different illnesses, peers etc.
Right Hand Side
Model of meiosis that demonstrates crossing over, segregation and
production of haploid gametes
 Experiment using plasticine, beads (blue and red), plastic plate,
plastic tray
 4 diff homologous pairs, repeat 4 times, record results and
compare to see if anyone got the same results
Demonstrate effect of environment on phenotype
 4 petri dishes with cotton wool, 10mL water, 50 wheat seeds
(from same batch) in each, 2 in dark, 2 in light, feed them every
3rd day with 5mL water, note progress
Outcome 4
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Describe the process of DNA replication and explain its significance
 First the strands separate – starting at one end, the hydrogen
bonds break between each base pair so that the two strands
unzip
 Form a ‘replication fork’ and binding proteins prevent the
strands rejoining
 A complementary copy of each exposed strand is constructed
from new nucleotides
 The process is catalyzed by the enzyme – DNA polymerase
 Anti-parallel strands  replicate in different manners
 Leading strand: the strand that is able to have its
complementary strand synthesized to it, in the SAME
DIRECTION as the dividing of the replication fork
 Lagging strand: the strand’s orientation is opposite to the
working orientation of the DNA polymerase  disallowing
continuous synthesizing of complementary strand
o Rather, DNA ligase, RNA primer and DNA primer work
together to form the complementary strand in small
separated segments
Outline, using a simple model, the process by which DNA controls the
production of polypeptides
Stages in polypeptide production
 Transcription
o DNA helix unwinds in the area of a particular gene
o Enzyme RNA polymerase moves along the strand, linking
complementary RNA nucleotides to form an mRNA
strand
o ‘met’ (start) and ‘stop’ codons control the length of the
mRNA strand
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o After the whole gene has been copied, mRNA strand is
modified so that is consists of only the base sequence
that will code for the protein – most genes contain noncoding regions known as introns
o Modified mRNA then moves through nuclear pores into
cytoplasm an introns are recycled for further use
Activation of amino acids
o In the cytoplasm, an enzyme attaches amino acids to their
specific tRNA molecules
Translation
o The mRNA strand enters a ribosome at the ‘start’ codon
end (AUG)
o 2 codons present in ribosome at any time
o A tRNA carrying the amino acid methionine (‘met’) at one
end and the anticodon UAC (opposite of AUG) at the
other, binds to the ‘start’ codon
o First amino acid and second amino acid, brought by
respective tRNA, bind to each other by dehydration
synthesis forming polypeptide bond
o The first tRNA is released from the ribosome and the
ribosome then moves along the mRNA strand one codon
at a time
o 2 tRNAs at a time are temporarily bound within the
ribosome and their amino acids linked (amino acids are not
necessarily entirely within the ribosome  irrelevant)
o Final triplet doesn’t code for any tRNA  mRNA roles of
ribosome, completing polypeptide chain
o A polypeptide chain is released into the cytoplasm
o A polypeptide chain is the only primary structure of a
protein
o Each protein has a particular conformation or shape
formed by the twisting or folding of its polypeptide chains
Relationship between proteins and polypeptides
 The polypeptide chain formed from the mRNA strand is a long
strip of corresponding amino acids
 If un-mutated, this polypeptide, either alone or with other
polypeptides, will move into a specific conformation, that which
is specific to the protein it is forming
 This conformation is the called the protein and it then performs
its specific designated job
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How mutations in DNA may lead to the generation of new alleles
 Mutation: Sudden change in chromosomal DNA which changed
the order of the nucleotide bases
 Mutagen: agent which brings about a mutation
 Only those occurring in cells producing gametes can be passed
on to successive generations
 Those in somatic cells only affect the individual and cannot be
passed on
 They can be harmful, neutral or beneficial
 Types of mutations:
 Point substitution:
o Substitution of a singular nucleotide
o The third cell in an anti-codon provides insurance against
point mutations having effect
o Due to the redundancy of mRNA code, some point
mutations in the last N base have no effect
o Sickle-cell anemia is caused by point substitution
 Triplet deletion or insertion:
o Causes the removal or insertion of an entire amino acid
from the chain
o Protein may not be able to fold into correct conformation
o Will effect reaction rate but effect may not be lethal
 Point deletion or insertion:
o Removal or insertion of a single N-base, causing frame
shift  every codon past the mutation will be nonsensical
o Results in a non-functional polypeptide
 Chromosome mutations examples:
o Aneuploidy: error in chromosome number by nonsegregation of a pair of homologous chromosomes
o E.g. down syndrome in non-sex cells or kleinfelters in sexcells
o Deletion of a length of code
o Duplication of a length of code
o Inversion of a length of code
o Translocation of a length of code
o Can all cause greatly impairing disease e.g. cystic fibrosis,
or could be lethal e.g. tay sachs
 Types of Mutagens:
o Chemicals e.g. herbicides, agent orange – interfere with
genes controlling celldivision
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

o Other chemicals cause tautomeric shift – affects N-bases
and change their chemistry causing them to connect with
the wrong partner  mostly 2 T’s connect rather than
connection with their corresponding A
o Radiation: e.g. x-rays, UV rays and radioactive sources
How do these mutagens affect?
o They can cause to T bases to connect to each other
o Can release free radicals which damage DNA by breaking
sidebars
o Mutagens can attach to DNA and stop it from working or
lie between strands stopping transcription taking place
When the gene is mutated, it calls for a different series of
amino acids  the polypeptide chain will fall into the wrong
conformation  it will do a different job  a new allele has
been formed
Evidence for the mutagenic nature of radiation
 1895: Rontgen discovered x-rays  one of his workers died of
skin cancer
 1896: Becquerel discovered nuclear radiation  had uranium in
his pocket and his skin burnt
 1896: Marie Curie discovered radium  died of cancer
 Most early workers with radiation died of cancer
 1905: Note that grape pickers in Europe had high incidence of
skin cancer on the back of their necks  overexposure to UV
rays
 1915: Some standards of protection for workers handling x-rays
and/or radioactive materials put into place
 1927: Muller showed radiation caused a mutation in Drosophila
 1928: International standards proposed for workers using
radiation/x-rays
 1945: Atomic bomb dropped in Japan in Hiroshima and Nagasaki:
o The new scientist: 45% of those who survived exposure
are still alive – being used as radioactive experiments
o Unborn children who were exposed to radiation grew
to be smaller and less intelligent than their peers
o Leukemia risk peaked after 10 years of exposure
o Higher exposure = higher risk of other diseases
o Pregnant women within 2km of ground zero either
miscarried or gave birth to premature babies who also
died
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o Study shows – colon, breast, stomach, and lung tumors
are more common in affected cities
o Radiation causes translocation of genetic material in
survivors – random translocations
1947: Marshall Islands – atomic bomb testing in Bikini Atol
1956-58: NZ forces on Malden Island for Atomic Bomb tests:
o Studies done shows: NZ sailors used as human guinea
pigs for genetic damage
o Of 551 veterans over 400 have died of cancer
o Rate of gametic abnormalities in children is 50%
compared to 3% in the lateral population
o Brits detonated nuclear bombs between 1950-58
o Average age of death for these sailors = 52.4 years
1962: Experiment done to demonstrate that UV light can cause
mutations in bacteria
o Cancer council: 90% skin cancer is caused by exposure
to UV light
1986: radiation near the oceans of Chernobyl affect physiology
of fish
o There was 20 times more radiation there than regular
o 2 species of fish turned from asexual to sexual
reproduction
Understanding of the source of variation in organisms has provided
support for Darwin’s theory of evolution by natural selection
 Mutation can be harmful, neutral or beneficial, those with
beneficial mutation will survive by natural selection, therefore
passing on their genes  evolution
 All mutations add to variation in gene pool – basis of evolution
by natural selection
Describe the concept of punctuated equilibrium in evolution and how
it is different from the gradual process proposed by Darwin


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Darwin’s theory of evolution proposes that populations change
slowly and gradually over time but this does not occur often
Fossil record suggests that most species appear suddenly, show
little change for millions of years and then become extinct
Eldridge and Gould explain this in their theory of Punctuated
equilibrium:
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o Instead of gradual transition over millions of years, there
have been periods of rapid evolutionary change followed
by long period of stability
o Suggests that when rapid change occurs in an
environment, organisms either move out of the area or, if
the change is sudden, die out
o Populations living away from the disturbed environment
may survive in small, isolated pockets
o These new forms migrate and appear suddenly as a new
species at different locations
o E.g. Globorotalia, a marine microfossil – a second species
appears as a fossil in the Indian and Atlantic Oceans but
a transitional form found between the two has been
found in the South Pacific Ocean – the two forms
coexist today
Right Hand Side
First-hand investigation: simple model for polypeptide synthesis
 Petri-dish = ribosome
 Strip of DNA code
 Write out strip of mRNA code
 Paper-clips = tRNA
 Beads = amino acids
 String amino acids together onto a thread
Beadle and Tatum’s ‘one gene – one protein’ theory – altered to ‘one
gene – one polypeptide’
 Beadle was experimenting in the 1930’s, with the Drosophila
fruit fly and it’s eye colour.
 Through series of experiments he suggested that the eye colour
in the fruit fly was a result of a series of chemical reactions and
somehow genes affect this series
 He found that this change in eye colour was due to the change
in a single protein
 He concluded from this that genes must influence heredity in a
chemical manner
 In the early 1940’s Beadle and Tatum published the results of an
experiment they performed to further look into the effects of
mutations of genes on organisms and they did this through
testing the pink bread mould called neurospora crassa
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They produced mutations in these organisms by exposing them
to large amounts of radiation and tested them
Those that were still able to survive on a minimal medium (salt,
sucrose and vitamin B) – which non-mutated bread mold could
survive on, were discarded from the experiment
All those that could not survive on this were then further
tested, they added single amino acids to the nutrient source of
various groups of mold and found that those that could not
survive on the minimal medium, could survive with the addition
of a singular, but specific amino acid - a
These that could survive off that amino acid could then be
divided into 2 groups, one that could survive off a different
amino acid –b and the other that could survive of another
amino acid – c
From this they suggested that the process used in forming an
amino acid necessary to maintain the survival of the organism
(usually carried out by the organism itself) was a 3 step series of
chemical reactions
If the amino acid A was needed then the chemical series that
needed to take place would require 3 enzymes, each produced
by a separate gene:
o Gene C would make enzyme C which would turn the
precursor into amino acid C
o Then gene B would make enzyme B that would turn amino
acid C into amino acid B
o Then gene A would make enzyme A turning amino acid B
into the final product needed, being enzyme A
o E.g Ornithine  Citrulline  Arginine
If one gene in this sequence was broken, then it would need to
amino acid that followed the broken gene to be added to the
organism, or the final product to be added
From this they formed the one gene, one enzyme hypothesis
This has since been developed and changed, as our knowledge
of proteins, enzymes, polypeptides and genes has grown, into the
one gene, one polypeptide theory
Changes in DNA sequences can result in changes in cell activity – see
mutation in DNA dot point
Modern example of natural selection
 Rabbits and Myxoma virus
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o Introduced in 1950 and eliminated 99% of rabbits
o By 1960, effectiveness was reduced to 50%
o In +/- 2000, Calici virus was introduced some success
with juveniles, but in the long term the same
reformation of population
o Need to use multiple weapons
Analyse relative importance of the work of, Watson, Crick, Franklin,
Wilkins, in determining the structure of DNA and the impact of the
quality of collaboration and communication on their scientific
research
 James Watson and Francis Crick
o Watson attended a lecture given by Wilkins  realised
that DNA had a regular crystalline structure and
together with Crick wanted to figure out the structure
o Went to a lecture by Franklin but incorrectly remembered
her data
o Made a model of DNA with N-bases inside the spiral 
Franklin laughed at this (partial communication)
o They did confirm the N-base pairing
o They worked out there were 10 steps for every 360 degree
turn
o Knew the A-T ratio was 1:1
o Knew each strand was a template for the other
o Worked out how DNA replicates
o Collaborated and communicated with each other, a bit
with Wilkins and barely with Franklin
 Rosalind Franklin
o Methodical, reserved lady, not respected by most of her
male colleagues
o One of the world’s most talented x-ray crystallographers
o Took pictures of both A (hydrated) and B (de-hydrated
DNA)
o De-hydrated DNA gave a clear picture of the signature
cross of the double-helix of the DNA
o Mathematically worked out the N-base pairing
o She could have made the discovery entirely on her own
but because of her absolute precision in her method it
took her longer to publish a paper therefore not receiving
the credit
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
o But she did confirm that Watson and Cricks paper was in
line with her findings – partial communication
o No collaboration – her work was stolen
o Her records show, evidence, mathematics and persistence
Maurice Wilkins
o Supervisor over Rosalind Franklin at King’s College
Laboratory – implied communication and collaboration
although minimal
o Noted that x-ray diffraction crystallography was the key
to finding the structure of the DNA molecule
o Found that DNA has crystalline structure
o He was the first to take photos of DNA and taught
Watson and Crick some of their skills –
collaboration/communication
o He did not actually contribute much in the way of work,
rather just being a messenger
Outcome 5
Identify how the following current reproductive techniques may alter
the genetic composition of a population:
 Artificial insemination:
o Sperm is collected from a male and inserted into the
vagina of a female  fertilizing the egg
o Useful in breeding because it increases the change that
the sperm with reach the egg
o Advantageous when it is costly to bring the male and
female together  sperm can be frozen in liquid nitrogen
and be transported around the world
o Used in agriculture to combine genetic make up of ideal
bull and cow etc
o Bringing genes together from around the world can
broaden a populations genetic variety
o Although if artificial insemination and selective breeding
can reduce chances of random crosses in a population 
reducing genetic variability in a population
o Practice in humans:
o If some sperm prove more desirable than other, then
genetic diversity in a population may be reduced, or could
lead to imbalance of sexes in families that choose the sex
of the baby
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o In reality, humans breed selectively naturally by choosing
sexual partners, some culture discard babies of a certain
sex  it is unlikely that artificial insemination will greatly
affect genetic variability
Artificial Pollination
o Plant breeders use artificial pollination to breed plants
with selected characteristics
o Pollen from male anther is brushed onto female stigma
and flower is then covered to prevent pollination by other
flowers
o Can be useful in breeding particular strains of plants
o Can reduce genetic diversity if it is used to breed a
population of plants with the same set of desirable
characteristics
Cloning
o Selective breeding relies on sexual reproduction  there
will always be some level of genetic variability
o Cloning is used to not just make similar organisms but
identical ones, mostly used by horticulturists/farmers
o Advantageous: because it makes maintenance simpler as
all have identical requirements, produces similar yields and
all under same conditions
o Disadvantageous: cloned crops are genetically identical in
every way  no genetic variety  they are susceptible to
the same diseases, and if one disease breaks out it will
devastate the entire population
o Leaves no potential for natural selection or evolution,
could make a species extinct
o Cloning has been used in mammals – Dolly the sheep
o Ethical issues in cloning humans  outlawed in many
countries
Process used to produce transgenic species
 Old fashion techniques
o Selctive breeding
o Plant cuttings
o Artificial insemination
o Artificial pollinations
o Embryo splitting  4 offspring instead of one, all clones
of each other
 Modern technology
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o Cloning  plants and animals
o Transfer of genes from one organism to another
Clones: identical genetic composition, e.g. plant cuttings,
embryo splitting/twinning
Purpose: to produce population of superior agricultural or
horticultural stock i.e large pop of identical organisms with
desirable fruits
o E.g. high meat/fat ratio, high milk yield, pest resistance,
long self life, better taste, herbicide resitance
o Bt Cotton contains a bacterial gene called Bacillus
thuringiensis (or Bt). It is a Gram-positive, soil-dwelling
bacterium, commonly used as a biological pesticide
because codes for a plant-produced protein that is
toxic to a number of pests such as cotton bollworm
and pink bollworm.
Because the cotton now contains Bt there is no need
to spray the crops and therefore the crops are not
affected.
o Golden Rice is a variety of Oryza sativa rice produced
through genetic engineering. It biosynthesizes betacarotene, a precursor of pro-vitamin A in the edible
parts of rice. Therefore it helps combat vitamin A
deficiencies which is the cause of millions of deaths to
pregnant woman and children particularly, world wide.
Micropropagation: the propagation of plants by growing
plantlets in tissue culture and then planting them out
Different methods of introducing foreign gene into an
organism:
Liposomes: small vesicles made of a single membrane  can be
made commercially to precise specifications
o When coated with appropriate surface molecules, they
are attracted to specific cell types in the body
o DNA carried by liposome can enter the cell by
endocytosis or fusion
o Can be used to deliver genes to these cells to correct
defective or missing genes  gene therapy
Plasmid vectors: naturally occurring accessory chromosomes
found in bacteria
o Through use of restriction enzyme, gene is able to be
cut from a healthy/normal gene and then annealed to
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plasmid by ligase enzyme after gene of plasmid has also
been removed by restriction enzyme
o This new ring of self-replicating DNA that is the
plasmid is now called a re-combinant
o Plasmid is then self-replicates once placed back inside
a bacteria
o GM insulin is created via combining a human insulin
gene into a plasmid that is found in bacteria. This
bacteria then multiplies quickly and produces large
amount of bacterium all producing human insulin. This
can then be used by diabetics to combat their inability
to produce insulin.
Viral vectors:
o Can accommodate up to 7500 bases of DNA inserted
in protein capsule
o When viruses infect and reproduce inside target cell 
also spreading the recombinant DNA
o Used for gene therapy
o Problem  hosts immune response to virus
Pronuclear injection: DNA produced directly into animal cell by
microinjection
o Multiple copies of desired transgene are injected into a
recently fertilised egg cell  transferred into surrogate
mother
o E.g. transgenic mice and livestock
o Inefficient  2-3% of eggs give rise to transgenic
animals and only a portion of them express added gene
adequately
o E.g. production of ATryn, using genetically altered
goats  first medicine produced using GM animals,
used to treat people with hereditary antithrombim
deficiency (suffer from excessive blood clotting)
o Milk-promoting DNA from goat and antithrombin
protein from humans are injected into fertilised goats
egg
o Goat will then produce high levels or antithrombin in
their milk  then purified to produce ATryn
Ballistic DNA injection: ‘gene gun’ shoots DNA directly into
living tissue of an organism
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o Microscopic particles of gold or tungsten are coated
with DNA  propelled by a bursts of helium into skin
and organs of animals and tissues of intact plants
o Some cells express DNA as if it were their own
Protoplast Fusion
o Requires cell walls of plants to be removed by
enzymatic digestion  protoplasts (cells having lost
their cell walls) are then treated with polyethylene
glycol  increases their frequency of fusion
o In new hybrid cell, DNA derived from the two ‘parent’
cells may undergo natural recombination
Potential impact of use of reproductive technologies on the genetic
diversity of species using named plant and animal example that have
been genetically altered
 Transgenic organisms have the potential to increase variety of
species  introduce genes from one species into another
 Creates potential for grater evolution
 Allows us to create population less likely to be destroyed by
adverse environmental conditions
 BUT  farmers select and grow GM species and fewer local
varieties are cultivated
  variety of alleles present in that crop plants are reduced and
those alleles which had been advantageous for local
environment are no longer present
 Solution: to maintain local variety, there are not local seed
banks to store seeds with alleles no longer being cultivated such
as cotton, tomatoes etc
 E.g. Bt Cotton is most commonly cultivated but this can also
lead to resistant pests  this whole variety of cotton will be
susceptible to the same weaknesses  destruction of cotton
worldwide  new GM cotton would have to be produced, using
seed banks
 E.g. dolly the sheep, and other artificially inseminated livestock
e.g. cows inseminated with ideal bull sperm
 Cloning of GM organisms  extreme situation where all
organisms are genetically identical  all equally susceptible to
same environmental factors  incapable of evolution
Right Hand Side
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Methodology used in cloning
Plasmid cloning:
1. Plasmind used as vector for gene transferred  plasmid e.g.
starts out resistant to two antibiotics, ampicillin and
tetracycline
2. Desired gene, e.g. for insulin, is taken from human
3. Chromosome holding gene is placed in solution containing
restriction enzyme specific to the base sequences it needs to
cut in order to remove exact insulin gene
4. Plasmid is extracted from bacterial cell
5. SAME restriction enzyme is used to cut open plasmid – gene for
ampicillin is cut out on same sequence of n-bases as insulin  it
is chosen specifically because of this
6. Sticky ends of insulin gene and that of plasmid with correspond
with each other
7. They are annealed together by ligase enzyme
8. Under the right conditions bacteria will re-absorb this plasmid
9. This bacteria is now a transgenic organism and the DNA is a
recombinant
10. Successful bacteria are either recognized by dye or samples
taken of each and can be identified by disrupted resistance to
ampicillin
11. Successfully modified bacteria are then left to reproduce 
making substantial amounts of insulin to then be injected into
diabetic humans
Examples of use of transgenic organisms and ethical issues around
them
Bt Cotton contains a bacterial gene called Bacillus thuringiensis (or
Bt). It is a Gram-positive, soil-dwelling bacterium, commonly used as a
biological pesticide because codes for a plant-produced protein that
is toxic to a number of pests such as cotton bollworm and pink
bollworm.
Because the cotton now contains Bt there is no need to spray the
crops and therefore the crops are not affected.
Golden Rice is a variety of Oryza sativa rice produced through genetic
engineering. It biosynthesizes beta-carotene, a precursor of provitamin A in the edible parts of rice. Therefore it helps combat
vitamin A deficiencies which is the cause of millions of deaths to
pregnant woman and children particularly, world wide.
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Page 33 of 34
GM insulin is created via combining a human insulin gene into a
plasmid that is found in bacteria. This bacteria then multiplies quickly
and produces large amount of bacterium all producing human insulin.
This can then be used by diabetics to combat their inability to
produce insulin.
ATryn producing goats  first medicine produced using GM animals,
used to treat people with hereditary antithrombim deficiency (suffer
from excessive blood clotting
Milk-promoting DNA from goat and antithrombin protein from
humans are injected into fertilised goats egg
Goat will then produce high levels or antithrombin in their milk  then
purified to produce ATryn
Ethical issues:
 Animal welfare
 Release of GMO’s into the environment can have unpredictable
effects  especially if they then breed with wild species e.g.
resistance to pesticides, herbicides, fungi  pests/weeds/fungi
could pick up these resistant genes, greatly affecting wildlife
 Labeling  should it be labeled as a GM product? Consumers
have the right to be informed  consumer backlash if they
found out
 Corporate monopolies  Monsanto has become dominant in
GM products
o They have made terminator species that disallow seeds to
be collected and re-planted so farmer has to buy again
ever year
o Gain control over GM market
o Issue if man with fully organic farm being sued because
neighboring farm’s GM pollen was blown over into organic
farm  who is in the wrong?
 Religious: man is playing the hand of G-d
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