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TOPIC: Genetics
Aim: Describe how to use punnett squares.
Do Now: next slide
HW: Study for tomorrow’s Reproduction
test!
BRING YOUR TEXTBOOK TO CLASS!
Pedigree Chart Reading notes due Wednesday!
Genetic Engineering Reading notes due Thursday!
Identify each
structure described.
1. Where pollen tube
forms B - Style
2. Produces pollen F - Anther
3. Where pollination
occurs A - Stigma
4. Will turn into fruit D - Ovary
5. Where fertilization
occurs C - Ovule
6. Will turn into seeds
C - Ovule
Embryo
Seed coat
Cotyledon
The trait for height in pea plants can be represented
by using the letter “T.” T represents the allele for
tall and t represents the allele for short.
a. What do we call the genotype for TT?
Homozygous dominant
b. What is the phenotype for TT? Tall
c. What do we call the genotype for tt?
Homozygous recessive
d. What is the phenotype for tt? short
e. What do we call the genotype for Tt?
Heterozygous
f. What is the phenotype for Tt? tall
The trait for seed color in pea plants can be
represented by using the letter “G.” G represents the
allele for green seeds and g represents the allele for
yellow seeds.
a. What do we call the genotype for gg?
Homozygous recessive
b. What is the phenotype for gg? yellow
c. What do we call the genotype for Gg?
Heterozygous
d. What is the phenotype for Gg? green
e. What do we call the genotype for GG?
Homozygous dominant
f. What is the phenotype for GG? green
Probability • The possibility
that an event
may or may not
happen
• Shows possible gene
Punnett combinations of offspring
Square
bw 2 organisms
Example:
1. T = tall
t = short
TT x tt
T
T
t T t Tt
t Tt
Tt
T
t Tt
T
Tt
t T t Tt
Phenotype=
100% tall
Genotype=
100% heterozygous
Example #2:
B = Black fur
b = white fur
Bb x Bb
B
b
B BB
Bb
b
bb
Bb
B
B BB
b
Bb
b B b bb
Phenotype= 75% black, 25 % white
Genotype= 25% homozygous dominant
25% homozygous recessive
50% heterozygous
Example #3:
Red is dominant in flowers & white
is recessive. Cross a
heterozygous flower with a
homozygous dominant flower.
•R = red
white
•Rr x RR
r =
Rr x RR
R
R RR
r
Rr
R R R Rr
Phenotype= 100% red
Genotype =
50% homozygous
dominant
50% heterozygous
TOPIC: Genetics
Aim: Practice using punnett squares.
Do Now: next slide
HW:
Pedigree Chart Reading notes due Monday.
Study for Tuesday’s Reproduction test.
One dog carries the
heterozygous, black fur trait
and the other carries
homozygous recessive white
traits. What are the chances of
having a puppy with black fur?
B = black, b = white
Bb x bb
Bb x bb
B
b Bb
b
bb
b B b bb
Answer: 50%
chance of having a
puppy with black
fur
The phenotype of an organism
1. represents its genetic composition
2. reflects all the traits that are
actually expressed
3. occurs only in dominant pure
organisms
4. cannot be seen
If an individual possesses two
recessive alleles for the same
trait, the individual is said to be
1. homozygous for the trait
2. haploid for the trait
3. heterozygous for the trait
4. mutated
The cell in Diagram 1 contains 4 chromosomes
and is undergoing the process of mitosis. What
is the total number of chromosomes in each
individual cell in Diagram 3?
1. 8
2. 2
3. 16
4. 4
In humans, which cell is produced by
mitosis (mitotic cell division)?
1.sperm cell
2.skin cell
3.egg cell
4.zygote cell
What would result if mitosis was not
followed by division of the
cytoplasm?
1.two cells, each with one nucleus
2.two cells, each without a nucleus
3.one cell with two identical nuclei
4.one cell without a nucleus
The diagram can be used
to show a process of:
1.making new body cells
for repair of tissue
2.making new sex cells
3.meiosis
4.sexual reproduction
The pistil of the flower includes the
1.stigma, anther, and filament
2.stamen, stigma and anther
3.stigma, style, and ovary
4.petals, sepals and pollen grains
1. Identify the process
represented in the
diagram. Meiosis
2.Where does this
occur? Gonads
3.Describe what happens
to the chromosome
number. Splits in half
4.Compare the daughter
cells to each other.
Not genetically similar
to each other
The blockages shown at A and B would
most likely interfere with the ability to
1. transport gametes
2. produce mature gametes
3. eliminate waste products through the
urethra
4. express secondary sex characteristics
Which statement is true of both mitosis and
meiosis?
1.Both are involved in asexual reproduction.
2.Both occur only in reproductive cells.
3.The number of chromosomes is reduced by
half.
4.DNA replication occurs before the division
of the nucleus.
Which statement about the
gametes represented in the
diagram below is correct?
1.They are produced by
females.
2.They are fertilized in an
ovary.
3.They transport genetic
material.
4.They are produced by
mitosis.
The process of meiosis formed
1.cell 1, only
2.cells 1 and 2
3.cell 3, only
4.cells 2 and 3