Download Document

TAKS Objective 2
Day 3
The student will demonstrate
an understanding of the
organization of living systems.
Genetics
Genetics is the study of
heredity.
Humans have 23 pairs of
chromosomes, which are composed of
DNA. Pieces of chromosomes are
known as genes.
You received one set of
chromosomes from your mother
(23) and one set from your father
(23), totaling 46 chromosomes.
Egg (from your mother)
Sperm (from your father)
Genes exist in alternative forms
called alleles. Alleles are
located on chromosome pairs.
Gene for
earlobe
(attached)
Gene for
earlobe
(unattached)
Chromosome from mother
Chromosome from father
Gregor Mendel
• It was not until the mid-nineteenth century
that Gregor Mendel, an Austrian monk,
carried out important studies of heredity—
the passing on of characteristics from
parents to offspring.
• Characteristics that are inherited are
called traits.
Pea Plants
• Mendel chose to use
the garden pea in his
experiments.
Traits are passed from
parents to offspring through
units of information or genes.
For each trait, an individual has two
factors (alleles): one from its mother
and one from its father.
RR
Rr
homozygous
heterozygous
If the factors are the same from both, you are
said to be homozygous for that trait. If the
factors are different, you are said to be
heterozygous. Each copy of a factor or
gene is called an allele.
A dominant gene will
override or mask the
recessive gene.
• An uppercase letter is
used for the dominant
allele and a lowercase
letter for the recessive
allele.
• The dominant allele is
always written first.
Short plant
Tall plant
T
T
t
T
t
t
F1
All tall plants
T
t
The physical appearance, phenotype,
of an individual is determined by the
allele that codes for that trait.
The set of alleles that an individual
has is called a genotype.
What the genes say…..
A Punnett square is used to
predict the possible genotypes
and phenotypes of the
offspring.
Punnett Squares
(Monohybrid)
Heterozygous &
Heterozygous
D
d
Heterozygous &
Homozygous Recessive
d
d
D
Dd
Dd
D
DD
Dd
d
dd
dd
d
Dd
dd
D
d
D
D
DD
Dd
Dd
Dd
D
D DD
Dd
Homozygous Dominant
& Heterozygous
d
d
Dd
Dd
Homozygous Recessive &
Homozygous Dominant
Dihybrid crosses allow us to
see when two traits from each
parent is being utilized.
AABB
AABb
AaBB
AaBb
AABb
AAbb
AaBb
Aabb
AaBB
AaBb
aaBB
aaBb
AaBb
Aabb
aaBb
aabb
Pedigree shows the Family Tree
male
female
If the shapes are
colored in, the
individual is affected
by the condition.
Incomplete dominance is
when two genes blend and
produce a third phenotype.
Red flowers
mate with
white flowers
to produce
pink flowers.
Codominance occurs
when both alleles are
expressed.
Roan cattle
are
codominant.
When traits are controlled
by more than two alleles in
a population, it is said to be
controlled by multiple
alleles.
Human blood type is controlled by
three different alleles.
In humans, there are four blood types
(phenotypes): A, B, AB, and O.
Blood type is controlled by three alleles,
A, B, and O.
A karyotype is a map of an
organism’s chromosomes.
Humans normally
have 23 pairs of
chromosomes.
Chromosomes occur in pairs.
The 23rd pair of chromosomes are sex
chromosomes. They determine the
sex of the individual.
Females – XX
Males - XY
If an individual is missing or
has too many chromosomes, a
karyotype can be used.
Trisomy – 3 chromosomes instead of 2
Monosomy – 1 chromosome instead of 2
An extra 21st
chromosome
is called
trisomy 21 or
Down’s
Syndrome.
A mutation is any change in
the DNA of a cell.
Mutations can be caused by:
1. Mistakes in replication
2. Mistakes in transcription
3. External agents
A mutation can only be
passed to offspring if it
occurs in the gamete.
Occasionally, a genetic
mutation can be beneficial
(helpful) to an organism.
The peppered moth
experienced a
beneficial mutation
which allowed it to
camouflage itself
to hide from
predators.
Question 1
Any change in DNA sequences is called a
_______.
A. replication
B. mutation
C. transcription
D. translation
The answer is B.
Learning Check
#2
What is a mutation?
A change in the DNA sequence
3.
Answer: A
Allele
Low-yield
High-yield
Rapidly maturing
Slow-growing
Tall
Short
Yellow kernels
White kernels
Symbol
H
h
M
m
T
t
Y
y
Answer: A
4. An agricultural scientist wants
to develop a variety of corn that
will mature rapidly and will
produce high yields. Which
genotypes should the scientist
cross to produce the most plants
with the desired characteristics?
A hhmmTtyy × hhMMttyy
B HHmmttyy × hhMMttyy
C hhMmttyy × HhmmttYY
D HHmmttyy × hhMmttYy
#5 The combination of alleles inherited is
called the genotype .
#6
The expression of traits is called the
phenotype
.
#7 If an individual inherits one dominant
allele and one recessive allele, the
genotype is heterozygous .
Taxonomy
Taxonomy is the science of
naming and classifying
organisms.
Classifying Organisms by name
• Binomial Nomenclature – naming
organisms using a two-part name.
–First word is the Genus (always
capitalized)
–Second word is the Species
(lower case)
Example: Homo sapiens
– Homo is the genus name.
– sapiens is the species name.
The scientific name of an
organism should always be
italicized or underlined.
Classifications
• Kingdom
Largest
• Phylum
• Class
• Order
• Family
• Genus
•
Species
Smallest
•
•
•
•
•
•
•
King
Phillip
Came
Over
From
Greece
Sneezing
Learning Check
#1 Which is the largest classification of
organisms?
A. Species
B. Genus
C. Family
D. Order
D
#2 Which is the most specific
classification?
A. Species
B. Genus
C. Family
D. Order
A
6 Kingdoms
•
•
•
•
•
•
Eubacteria
Archaebacteria
Protista
Fungi
Plantae
Animalia
Prokaryotes
Eukaryotes
Archaebacteria
• Includes only prokaryotes
• Archaebacteria live without oxygen;
in extreme habitats (salt lakes,
swamps, deep ocean thermal vents,
hot springs)
Eubacteria
• They too are prokaryotic, meaning
they have no membrane-bound
nucleus.
• Some use cilia or flagella to help them
move.
Bacteria are classified according to
their shape.
Cocci – round
Bacilli – rod shaped
Spirillum – spiral
shaped
Eubacteria can cause disease
Diseases caused by Eubacteria include:
– Tetanus, typhoid fever, tuberculosis,
strep throat, and staph infections.
Antibiotics are used to treat
bacterial infections.
Antibiotics are useless against viruses!
The spread of harmful bacteria
can be avoided by:
1. Washing your hands thoroughly
with soap and water.
2. Covering your mouth and nose
when sneezing and/or coughing.
3. Limiting the number of times you
touch your face, mouth, eyes, and
nose.
4. Cooking foods properly.
Most Eubacteria do not cause
infection or disease.
Some bacteria are helpful by:
1. Aiding in the digestion process
2. Nitrogen-fixing bacteria helping plant
roots grow
Yogurt and swiss cheese
are made with the help of
bacteria.
Bacteria are decomposers.
Decomposers
help break
down dead
and decaying
matter.
Learning Check
#1
How are bacteria classified?
According to their shape
#2 An organism is single celled, does
not have a nucleus, and lives in a
deep sea thermal vent. What
kingdom does it most likely belong to?
A. Plantae
B. Archaebacteria
C. Eubacteria
D. Animalia
B
Learning Check
#3 A prokaryotic cell is found that causes
diptheria. What kingdom would this
organism belong to?
A. Plantae
B. Archaebacteria
C. Eubacteria
D. Animalia
C
#4 How would you classify a bacteria that
was rod-shaped?
A. cocci
B. bacilli
C. spirilli
B
Kingdom Protista
• Eukaryotic
• Unicellular &
Multicellular
• Most diverse
group of all the
kingdoms
• Found mainly in
moist environments
• Ex: amoebas
Protists are eukaryotes.
Eukaryotic cells have a true
nucleus and other cell
organelles.
Kingdom Fungi
•
•
•
•
Eukaryotic
Most are multicellular
Many are decomposers
Ex: mushrooms, yeast,
& mold
Kingdom Plantae
• Multicellular Eukaryotes
• Stationary (cannot move around)
• Have cell walls made of cellulose.
Plants are autotrophs.
Plants can make
their own food by
way of
photosynthesis.
Plants have chloroplasts in
their cells, which allow the plant
to convert the energy from
sunlight into chemical energy
for the plant.
The chloroplasts contain
a green pigment called
chlorophyll.
What is required for
photosynthesis to take
place?
1. Sunlight
2. Water
3. Carbon Dioxide
Kingdom Animalia
• Multicellular Eukaryotes
• Consumers or Heterotrophs
• Mobile – can move from
place to place
• No cell walls
• Have tissues that are
organized into organs and
organ systems
Animal cells do not have
cell walls.
Learning Check
#1 A scientist discovers a
multicellular eukaryotic organism that
moves to obtain food. What kingdom
does it most likely belong to?
A. Plantae
B. Archaebacteria
C. Eubacteria
D. Animalia
D
2. A group of scientists discover a new species in a rain
forest. They take a tissue sample from one of the organisms
and look at it under a microscope. The cells making up the
tissue have nuclei and cell walls. Next the scientists take
several of the organisms and place them in damp soil that is
rich in organic material. Half of the organisms are exposed
to full sunlight, and half are kept in constant darkness. The
group that receives sunlight grows and thrives, but the
group that is kept in darkness gradually dies. In which
kingdom should the new species be classified?
A Eubacteria
B Fungi
C Plantae
D Animalia
Answer: C
3. Which of these
classifications
is most specific?
A Family
B Genus
C Phylum
D Order
Answer: B
4. Some bacteria benefit mammals
by helping with• —
Kingdom Bacteria has
F growth
G defense
H digestion
J respiration
beneficial and harmful
members
• The best answer here
is H, since digestion
systems of mammals
contain bacteria.
• Bacteria found in the
respiratory system
usually result in
illness, which would
trigger the defenses,
not help them.
5. The bacteria Bacillus thuringiensis produce
protein crystals that are toxic to the digestive
system of insects. How can these bacteria be used
to control insects in crops?
F
G
H
J
Apply the bacteria to growing plants.
Expose the bacteria to low levels of light.
Remove plants from areas containing the
bacteria
Treat the bacteria with a solution of the
protein crystals
Answer: F
6. The bullfrog, Rana catesbeiana,
is most closely related to the —
F spotted chorus frog, Pseudacris clarki
G Asian flying frog, Polypedates leucomystax
H northern leopard frog, Rana pipiens
J African bullfrog, Pyxicephalus adspersus
Related in biological terms means
family, genus, species.
F spotted chorus frog,
Pseudacris clarki
G Asian flying frog,
Polypedates
leucomystax
H northern leopard frog,
Rana pipiens
J African bullfrog,
Pyxicephalus
adspersus
• Genus is always a
capital letter,
species is lower
case.
• Most closely
related would be in
the same genus,
Rana.
• ANSWER?
• H
C
TAK Obj. 02
TEKS
B.8C