Download Classical / Mendelian Genetics

November 30, 2011
Classical / Mendelian
Genetics
Inheritance Patterns
November 30, 2011
Mendel
Re-Enactment
Axial vs. Terminal
Flowers
What will the genotypic & phenotypic
ratios of the offspring be?
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What will the genotypic & phenotypic
ratios of the offspring be?
What will the genotypic & phenotypic
ratios of the offspring be?
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Complete practice examples #1-5
from your booklet pages 6 and 7
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Complete practice examples #6-9
from your booklet pages 7
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Complete practice examples
#10-13 from your booklet page 8
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Complete practice examples
#14-16 from your booklet page 9
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1 What will the phenotypic
ratio of the F1 offspring
be?
___ White: ___ Black
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2 What percentage of the F1
offspring would you
expect to be white?
3 What will the genotypic
ratios of the F1 generation
be?
___ BB: ___ Bb: ___ bb
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4 Suppose a true-breeding right handed person and
a true-breeding left handed person had children.
What percentage of their children would be right
handed?
5 Suppose two heterozygous individuals had
children, what percentage of the offspring would
be left handed?
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6 Suppose two heterozygous individuals had children.
What percentage of the children would you expect to
have the homozygous dominant?
7 A couple have 9 children. Of the 9 children, 7 can
roll their tongues, and 2 can't. What are the
possible genotypes of the parents? Choose all
answers that are possible.
A
Father: tt
Mother: tt
B
Father Tt
Mother Tt
C Father TT
D Father Tt
Mother tt
Mother tt
Which is most likely?
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Testcross Example
Black wool is very brittle and is difficult to dye. A rancher an
avoid getting black sheep in his flock by only breeding
homozygous dominant sheep (WW). The rancher first has to
determine if his white sheep are actually homozygous. Show
how he could determine the unknown genotype of his white
sheep by using a testcross.
Multiple Alleles Example
You are in the process of performing genetic experiments on flies in
the lab when all of your flies escape. You manage to trap a couple
of flies but you no longer know what genotype they are. One of the
flies has red eyes, and the other has white eyes. You perform a
testcross with the two and half of the resulting progeny have apricot
eyes.
What was the genotype of your parent flye with red eyes?
Will any of your progeny have white eyes? Explain
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Incomplete Dominance
8 There are two possible alleles for snapdragon colour, CR (red)
and CW (white). These two alleles exhibit incomplete
dominance and the phenotype of a heterozygous snapdragon
(CRCW) is pink. If you were to cross a red snapdragon with a
white snapdragon, what would be the colour distribution of the
F2 generation?
___ Red: ___ Pink: ___ White
Co-Dominance
9 What percentage of the
offspring would you
expect to be roan?
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Co-Dominance
10 What percentage of the
offspring would you
expect to be red?
Blood Type Example
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11 This couple can have children
with which blood types? Choose
all that are possible.
A
A
B
B
C AB
D
O
12 Human blood type is determined by co-dominant
alleles as well as dominant / recessive alleles.
A B
There are three different alleles known as I , I ,
A
B
and i. The I and I alleles are co-dominant, and
the i allele is recessive. A woman with type A
blood and a man with type B blood could
potentially have offspring with which blood types?
A
A
B
B
C AB
D
O
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Sex-Linked Examples
13 In cats an X-linked gene helps to determine colour.
Homozygous R genotypes produce orange cats,
homozygous r genotypes produce black cats, and
heterozygotes are tortoise-shell colour. What percentage of
the offspring from the following cross are expected to be
orange?
XRXr
R
X Y
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14 Females resulting from
this cross will be:
A
50% black
B
100% black
C 50% orange
D 100% orange
E
50% tortoise shelled
F 100% tortoise shelled
XrXr
Mendel's Law of Independent
Assortment
XRY
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15 In pea plants, yellow seed colour is dominant to
green seed colour and round seeds are dominant to
wrinkled seeds. If a homozygous yellow-round
seed is crossed with a homozygous green-wrinkled
seed, what percentage of the F1 generation will be
yellow and wrinkled?
X
16 If two of the F1 heterozygous
plants (YyRr) from the previous
question are crossed, what will
the ratio of the F2 plants be?
X
YyRr
YyRr
___ Yellow Round: ___ Yellow Winkled: ___ Green Round: ___ Green Wrinkled
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Feather colour in parakeets is
controlled by two genes. For one
pigment gene, the B allele produces
blue colour, and the b allele does not
produce any colour at all. For the other
pigment gene, the Y allele produces
yellow colour and the y allele does not
produce any colour at all. Any
genotype containing at least one B and
one Y will produce a green parakeet.
1. Which of the following parental genotypes could produce
offspring displaying all four different colour patterns?
a. BBYy x BbYy
b. BbYY x Bbyy
c. bbYY x bbyy
d. Bbyy x bbYy
Feather colour in parakeets is
controlled by two genes. For one
pigment gene, the B allele produces
blue colour, and the b allele does not
produce any colour at all. For the other
pigment gene, the Y allele produces
yellow colour and the y allele does not
produce any colour at all. Any
genotype containing at least one B and
one Y will produce a green parakeet.
2. What is the probability of obtaining a blue parakeet when two
green heterozygous parakeets are crossed?
a. 0
b. 3/16
c. 1/4
d. 9/16
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Enlarge for 2nd Question
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Linked
Genes
PowerPoint
November 30, 2011