Download Goal 3: The learner will develop an understanding of the continuity

EOC Review 08-09
Goal 3: The learner will develop an understanding of the continuity of life and the
changes of organisms over time.
-DNA-Deoxyribonucleic acid. The blueprint of life. Found in the nucleus. Takes the shape of a double
helix. Composed of repeating units called nucleotides. Each nucleotide has 3 parts
1. sugar (deoxyribose)
2. phosphate
3. a nitrogen base (adenine, cytosine, guanine, thymine)
-Complementary base pairing: A-T, C-G
- The two strands of the DNA molecule are held together by hydrogen bonds formed between
complementary nitrogen bases.
-DNA, like a blueprint, contains information for cells to function, and for the organism made up of those
cells to function as a whole. It does these things by determining the proteins that will be produced by
certain cells.
- The double helix model of DNA structure was developed by Watson and Crick.
-Replication- process by which DNA is duplicated before a cell divides. The end result of replication is
two molecules of DNA, each of which contains one old strand and one new strand. Replication of DNA
must take place before cells can divide. It allows daughter cells to have an exact copy parental DNA.
Mutation – a change in the DNA sequence.
Mutation is the original source of variation
and may be helpful, harmful, or have no
effect.
Mutation can lead to the production of
a nonfunctional protein.
Several common types of mutations are
shown in the diagram at the right.
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EOC Review 08-09
PROTEIN SYNTHESIS
- linking amino acids in the proper order to make a functional protein
-transcription- the process of copying DNA code onto mRNA. Transcription takes place in the nucleus.
Following transcription, mRNA travels to the ribosome where translation takes place.
-translation-synthesis of a polypeptide from the information carried by mRNA. Translation takes place in
the cytoplasm on the ribosomes.
-RNA-Ribonucleic acid. Thymine is replaced by Uracil. Complementary base pairing:
A-U,
C-G
3 types of RNA
mRNA- messenger RNA. Copies the DNA code.
tRNA- transfer RNA. Picks up amino acids and transports them to the ribosome.
rRNA- ribosomal RNA. Structural component of the ribosome.
Sequence of events in protein synthesis
- mRNA copies DNA (transcription)
- mRNA carries DNA code to ribosome
- tRNA brings correct amino acids to mRNA at ribosome (translation)
- amino acids join to form a protein (polypeptide)
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EOC Review 08-09
-Know how to read the following chart.
U
C
A
G
-
U
Phe
Phe
Leu
Leu
Leu
Leu
Leu
Leu
lle
lle
lle
Met
Val
Val
Val
Val
C
Ser
Ser
Ser
Ser
Pro
Pro
Pro
Pro
Thr
Thr
Thr
Thr
Ala
Ala
Ala
Ala
A
Tyr
Tyr
stop
stop
His
His
Gin
Gin
Asn
Asn
Lys
Lys
Asp
Asp
Glu
Glu
G
Cys
Cys
stop
Trp
Arg
Arg
Arg
Arg
Ser
Ser
Arg
Arg
Gly
Gly
Gly
Gly
U
C
A
G
U
C
A
G
U
C
A
G
U
C
A
G
codon- series of three nitrogen bases or nucleotides that codes for a specific amino acid.
EX: AAG = lysine
UGA = stop
GUU = valine
- If DNA is copied incorrectly, the wrong amino acid may be placed in a protein, or in the case of a frameshift mutation, everything from the mistake forward may be incorrect.
CELL DIVISION
-Cell cycle = interphase + mitosis + cytokinesis
- interphase – preparation for cell division- cell
grows and DNA is copied.
- mitosis – division of the nucleus
- cytokinesis- division of the cytoplasm.
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EOC Review 08-09
MITOSIS
-surface to volume ratio- the outer surface of a cell
grows more slowly than the volume of material
inside the cell. When the surface of a cell is no
longer large enough to let in the proper amounts of
food and let out wastes, the cell divides. The two
smaller cells have a larger ratio of surface area to
cell volume and are able to function better.
-mitosis- Makes an exact copy of parent cell. Is used for
growth or replacement of cells in multicellular
organisms, and reproduction in unicellular
organisms.
- Be able to put diagrams of phases in correct order
and describe what is happening in each phase.
- Be able to tell what is happening with chromosome
number at each step.
-know how animal mitosis differs from plant mitosis
Plant
Do not have centrioles
Divide by laying down
a cell plate
Animal
Do have centrioles
Divide by pinching in
half (cleavage
furrow)
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EOC Review 08-09
MEIOSIS
Meiosis
- Used to produce cells with
half the number of chromosomes
found in the parent cell (gametes
such as sperm and egg cells).
- Review diagram- know how to
put diagrams in order, what is
happening in each phase, and how
the chromosome number changes
from phase to phase.
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EOC Review 08-09
MITOSIS
MEIOSIS
All body cells
Certain cells of reproductive organs
NUMBER OF CELLS PRODUCED
PER PARENT CELL
CHROMOSOME NUMBER OF
PARENT CELL
Two
Diploid or haploid
Four (in egg cells three will die,
leaving only one)
Diploid (2n)
CHROMOSOME NUMBER OF
DAUGHTER CELL
Same as parent
Haploid (n)
Various somatic cells such as
skin and bone
Genetic continuity from cell to
cell
Animal gametes (sperm & egg) or
certain spores
Promotes variation and genetic
recombination
OCCURS IN
KIND OF CELL PRODUCED
FUNCTION
SEXUAL VS. ASEXUAL REPRODUCTION
-Asexual reproduction occurs among members of all kingdoms and in general is the only means of
reproduction used by monerans (bacteria). All methods of asexual reproduction result in the
production of offspring that are identical to the parent and to one another. Asexual reproduction is
an advantage for organisms that live in a constant unchanging environment because it produces
organisms just like those that are already well adapted to the environment. Methods of asexual
reproduction include:
-binary fission- type of asexual reproduction in which an organism divides to produce two
identical daughter cells. (bacteria or paramecium)
-budding or vegetative reproduction- asexual reproduction in which a new organism is
produced by means of an outgrowth that breaks off from the parent. Occurs in hydra and yeast.
-fragmentation- asexual reproduction in which whole new adults are formed
from fragments of the original organism by regeneration. (sponge or starfish)
-spore formation- a spore is a reproductive cell capable of developing into a new haploid
organism without first fusing with another cell. (fungi)
-parthenogenesis a process in which the egg develops into an offspring without being fertilized.
Organisms produced by parthenogenesis are often haploid, but may be diploid as the result of the
formation of special diploid zygotes. Ex: Male honeybees (drones) are produced
parthenogenically. Females (both sterile workers and queens) are produced by from fertilized eggs.
- Vertebrate Ex: There are 15 species of whiptail lizards that reproduce parthenogenically. They are
all females.
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EOC Review 08-09
-Sexual reproduction-involves gametes that combine DNA and produce offspring different
from one another and from the parents. Sexual reproduction is an advantage in a changing environment
because it allows for variation and genetic recombination, which are necessary for evolution. During
gamete production genetic variation is increased through crossing over and independent assortment of
chromosomes.
-conjugation- a form of sexual reproduction carried out by bacteria, some algae, and fungi. It
involves the transfer of genetic material from one cell to another by cell-to-cell contact.
(paramecium)
-Plants have a life cycle in which the sporophyte and gametophyte generations alternate with one
another. The diploid sporophyte generation is the major stage in Angiosperms.
-Animals do not undergo alternation of generations, and only their gametes are haploid
-Eggs of animals may be fertilized either internally or externally.
GENETICS
- Gregor Mendel- the father of genetics. Developed the laws and principle listed below.
-Conducted research with pea plants.
The Principle of Dominance- when you cross a homozygous dominant with a homozygous recessive,
all the offspring will exhibit the dominant trait.
The Law of Segregation- While each individual carries a pair of factors for a given trait, during gamete
formation the two alleles are segregated and only one goes into each gamete.
The Law of Independent Assortment- factors for different characteristics are distributed to gametes
independently. The exception to this is when the genes for different traits are carried on the same
chromosome.
Gene linkage- when genes are carried on the same chromosome they are said to be linked or belong to
the same linkage group.
-phenotype- a term used to designate the physical appearance of an organism and distinguish it from its
genetic make up.
- genotype - a term used to designate the genetic composition and distinguish it from the appearance
(phenotype)
-homozygous- the condition of having two identical alleles. Ex: HH, or hh
-heterozygous- the condition of having two different alleles. Ex: Hh
-know dihybrid cross
TTYY X ttyy
TTYY
TY
ty
TY
TY
TtYy
TtYy
TtYy
TtYy
All gametes
ty
ttyy
ty
All gametes
All offspring 100% Dihybrid
TtYy
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EOC Review 08-09
TtYy X
TtYy
TtYy
TY
Ty
tY
ty
Possible Gametes
TY
TY
TTYY
Ty
tY
ty
TTYy
TtYy
TtYy
Ty
TTYy
TTyy
TtYy
Ttyy
tY
TtYY
TtYy
ttYY
ttYy
ty
TtYy
Ttyy
ttYy
ttyy
****Remember the phenotypic ratio for this one is 9:3:3:1
-
Dominant allele – form of a trait that masks the expression of the recessive allele
Recessive allele– form of a trait that is masked by the dominant allele
- Test Cross – Cross an organism of dominant phenotype and unknown genotype with an organism that
is homozygous recessive. If any of the offspring exhibit the recessive phenotype, the unknown genotype
parent must be heterozygous.
-Incomplete dominance- inheritance pattern where the phenotype of a heterozygous individual is
intermediate between those of the two homozygotes. The genotype of the individual is obvious from the
phenotype. Ex: red, white, and pink snapdragons.
-Codominance- pattern of inheritance where the phenotype of a heterozygous individual shows the
expression of both alleles. EX: checkered chicken, or roan horse. Also human blood types. The
genotype can be determined by observing the phenotype.
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EOC Review 08-09
Multiple alleles- even though each individual carries only two alleles for a given trait, there are more
than two alleles for the trait in the population. Ex: A,B,O, blood groups.
Blood Type
Possible Genotype(s)
A A A
A
I I ,I i
B
IBIB, IBi
AB
IAIB
O
ii
Show the likely results of a cross between a man with type AB blood and a woman with type O blood.
IAIB x ii
IA
IAi
IAi
IB
IBi
IBi
Charles Drew -developed a system to produce plasma, separating it from the blood matter. In 1941, he
became the first medical director of the first American Red Cross Blood Bank in the United States,
which produced dried plasma that could be preserved longer than the liquid plasma. The pioneering
medical work of Dr. Drew, a distinguished African American, saved the lives of thousands of wounded
Allied serviceman during the Second World War.
Polygenic Inheritance - a pattern of inheritance in which many genes affect a single trait.
- Ex: Genes A, B, and C control skin color. If the dominant alleles code for darker skin
and the recessive alleles code for lighter skin, the following pattern would result.
- Genotype
Phenotype
- AABBCC
darkest skin
- AaBBCC
very dark skin
- AaBbCC
dark skin
- AaBbCc
medium skin
- aaBbCc
light tan skin
- aabcc
very pale skin
Traits controlled by polygenic inheritance usually show continuous variation
Continuous variation- gradations in traits ranging from one extreme to the other with the
largest number of individuals exhibiting the phenotype that is mid way between the extremes.
(Ex: colors of hair, skin color, eye color, height). A graph of phenotype vs. number of
individuals will take the shape of a bell curve.
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EOC Review 08-09
GENETIC DISORDERS TO KNOW
DISORDER
SYMPTOMS
Cystic Fibrosis
Sickle cell
anemia
Tay-Sachs
disease
Phenylketonuria
Hemophilia
Huntington’s
Disease
Muscular
dystrophy
Mucus clogs lungs,
liver, and pancreas;
usually don’t survive to
adulthood
Poor blood circulation
Deterioration of central
nervous system in
infancy; usually don’t
survive to adulthood.
Failure of brain to
develop in infancy;
usually don’t survive to
adulthood if untreated.
If treated with special
diet from birth,
individual will develop
normally
Failure of blood to clot
Gradual deterioration
of brain tissue in
middle age; shortened
life expectancy
Wasting away of
muscles; shortened life
expectancy
DEFECT
Failure of chloride
ion transport
mechanism
DOMINANT
OR
RECESSIVE
Recessive
FREQUENCY
1/1,800
(whites)
Abnormal
hemoglobin
molecules
Defective form of
enzyme
hexosaminidase A
Recessive
Defective form of
enzyme
phenylalanine
hydroxylase
Recessive
1/18,000
Defective form of
blood clotting factor
IX
Production of an
inhibitor of brain
cell metabolism
Sex-linked
recessive
1/7,000
Muscle fibers
degenerate and
atrophy
Sex-linked
recessive
Recessive
1/1,600
(African
Americans)
1/1,600
(Jewish)
1/10,000
Dominant
1/10,000
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EOC Review 08-09
-Sex-linked traits- traits controlled by genes located on one of the chromosomes that determine the sex
of the individual. Most sex-linked traits are carried on the X chromosome, rather than the Y because the
X chromosome is much larger than the Y.
Examples : Color blindness, hemophilia, Duchene Muscular Dystrophy, Eye color in flies
Example of Sex-linked Cross: Red-green colorblindness
Husband, color blind X Wife, normal color vision
XcY
Xc
XC
XC
XCXc
Normal color
vision
XC
Female
carrier
XCXc
Normal color
vision
XC
Female
carrier
X
XCXC
Y
XCY
Normal color
vision
Male
XCY
Normal color
vision
Male
Genotypic ratio
2/4 or 50% XCXc
2/4 or 50% XCY
Phenotypic Ratio
2/4 or 50% Female carriers w/
normal color vision
2/4 or 50% Males with
normal color vision
-pedigree- a chart showing how a trait is inherited in a family
- most genetic disorders are caused by recessive genes.
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EOC Review 08-09
-Karyotype- photograph of the chromosomes of an organism. Used to detect certain chromosomal
abnormalities such as Down Syndrome. Also shows gender of individual. A karyotype can be produced
using material withdrawn during amniocentesis.


Note – 3 copies of the 21st
chromosome = Down
Syndrome which is caused by
non-disjunction.
Note – 23rd pair of
chromosomes = sex
chromosomes. XX = female
XY = male
DNA TECHNOLOGY
- used in forensics, medicine, and agriculture.
The Human Genome Project- The international effort to completely map and sequence the human
genome which is the approximately 35,000 to 40,000 genes on the 46 human chromosomes. The project
is useful in determining whether individuals may carry genes for genetic conditions and in developing
gene therapy.
gel electrophoresis- separation of DNA fragments by length. Used to produce a DNA fingerprint which
can be used to identify individuals, determine parentage, or as evidence in a crime.
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EOC Review 08-09
-plasmid- small circular pieces of DNA in
some bacterial cells that is often used in
genetic engineering.
-recombinant DNA- DNA molecule that
forms from the combination of portions of
two different DNA molecules.
- transgenic organism- organism containing
DNA from another organism.
The process shown in this diagram is used to
produce human insulin and human growth
hormone.
Clone – exact genetic copy
gene therapy-the treatment of genetic diseases by introducing normal genes into body cells. Viruses are
often used as a vehicle to insert the donor DNA into the defective cell. Working on a way to use this to
treat cystic fibrosis.
Be aware that there are ethical implications and possible dangers in biotechnology.
Analyze and explain the role of genetics and environment in health and disease.
Interaction between genetics and environment ultimately determine human health.
-There are purely genetic conditions: sickle cell, colorblindness, cystic fibrosis, hemophilia, Down
syndrome (trisomy 21), and Huntington’s disease.
- There are conditions with genetic and environmental components such as; cardiovascular disease,
diabetes, cancer, and asthma.
- There are conditions with primarily environmental causes such as malnutrition and lead poisoning.
- Some common environmental risk factors include radiation and tobacco smoke.
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EOC Review 08-09
EVOLUTION
Abiogenesis or Spontaneous generation – The belief that living things could arise from non-living
things (maggots from rotting meat)
Biogenesis – The belief that life comes only from other life. This was proven by Louis Pasteur using
the curved neck flasks which allowed air to enter and exit the container, but prevented contamination
from reaching the broth inside.
Earth’s early atmosphere did not contain oxygen.
-Stanley Miller and Harold Urey- conducted an experiment to show how organic matter may have
formed in Earth's primitive atmosphere and how the first life forms may have come to be.
-Miller recreated what he thought might have been Earth's earliest atmosphere by mixing methane
ammonia, water and hydrogen in a flask. He then exposed the contents of the flask to electric sparks to
simulate sunlight and lightening on primitive Earth. After several days Miller found several amino acids
as well as urea, acetic acid and lactic acid.
-Miller showed that organic matter such as amino acids could have formed spontaneously in the
conditions present on primitive Earth.
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EOC Review 08-09
The first organisms on Earth are believed to have been heterotrophic and prokaryotic.
-Over time organisms evolved from very simple to very complex.
- Humans and dinosaurs were not on Earth at the same time!
EVOLUTION
Charles Darwin is credited with developing the theory of Evolution by means of Natural Selection
-The finches Darwin observed on the
Galapagos Islands were of 14 different
species. While they varied in size, feeding
habits and beak structure, they had many
characteristics in common. Darwin
believed they were all descended from a
species of finch commonly found on the
mainland. He believed a flock of mainland
finches had been blown to the island by a
storm. Depending on which island a bird
inhabited and the type of food that was
available there certain beak structures
would be favored over others. Through
natural selection the favored beak type
would become the predominant beak for
finches on that island. Since the birds did
not fly from one island to another, over a
period of many years the ancestor finch evolved in different directions to produce the different species
seen on the different islands.
- Evidence for evolution
1. Fossil record
- Relative dating vs. absolute dating
2. comparative anatomy
-homologuos structures- parts of different organisms, often quite dissimilar, that
developed from the same ancestral body part.
Not all homologous structures serve important
functions, in fact they may be just vestiges or traces of what
they were in an ancestral organism. This type of organ is
called a vestigial organ. Examples of vestigial organs
include the human tailbone and appendix, and the vestiges of
leg bones in some snakes.
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EOC Review 08-09
3. comparative embryology- the study of developing
organisms. Relationships not always visible in the fully
developed organism may be more clearly seen by
looking at the developing organisms. The more alike the
development of two organisms is the more closely
related they are thought to be.
4. comparative biochemistry- the more closely related
two species are, the more closely their
important chemical compounds resemble each
other. (EX: comparing the amino acid sequence in
the hemoglobin of two different organisms)
5. comparison of DNA
The more similar the DNA sequences of two organisms the more
closely related they are believed to be.
- Remember variation provides the raw material necessary for natural selection and evolution.
-divergent evolution- when one species evolves into two or more species with different characteristics.
-adaptive radiation-divergent evolution and adaptation of a species over time in response to a new
environment. (EX; Darwin's finches)
-geographic isolation- geological change (Ex; formation of a river, canyon, or mountain) that isolates
segments of a population. If conditions are different in the two newly separated regions then the two
newly separated groups may evolve in different directions and eventually become different species.
Reproductive isolation- occurs when formerly interbreeding organisms can no longer produce fertile
offspring due to an incompatibility of their genetic material or by differences in mating behavior.
-speciation- evolution of a new species.
-population- collection of individuals of the same species in a given area whose members can breed
with one another. In order to be considered the same species, organisms must be able to interbreed and
produce fertile offspring.
-selective breeding- method of improving a species by choosing animals or plants that have desirable
characteristics to produce offspring with those desirable traits.
-England's Peppered Moths- An Example of Natural Selection
-Excellent example of natural selection in action.
-The peppered moth spends much of the daytime resting on the bark of oak trees. In the early
th
19 Century most of the oak trees in England were light brown speckled with green, and most of the
peppered moths were of the same coloration. There were also a few dark colored moths, but not very
many.
-When the industrial revolution began in England, pollution (mostly soot from burning coal) turned the
tree trunks dark brown. At about the same time biologists noticed that more and more moths of dark
coloration were appearing.
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EOC Review 08-09
-Reason for the change: natural selection. The moths served as food for the birds. When a moth had the
same coloration as the tree trunk it was much harder for the bird to see, and thus much less likely to be
eaten and much more likely to survive.
Antibiotic resistant bacteria
Some bacteria possess a mutation that makes them resistant to certain antibiotics. When the population
of bacteria is exposed to antibiotics most of them will die, but those with the mutation will survive.
When they reproduce they are likely to pass the mutation on to their offspring. Eventually there is a
population of antibiotic resistant bacteria.
Pesticide resistant insects
Same situation as antibiotic resistant bacteria.
-adaptation - process that allows organisms to become better adapted to their environments, or a trait of
an organism that helps it survive in its environment.
-convergent evolution is a process in which species that are not closely related, but live in similar
environments evolve similar traits. (Ex; Dolphins are mammals, not related to fish, but they have a
streamlined body shape like that of a fish.)
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