Bio340Quiz 6 Due
April 5th by 11:59 pm
1) In watermelons, bitter fruit (B) is dominant to sweet fruit (b), and yellow spots (S) are
dominant to no spots (s). The genes for these two characteristics assort
independently. A homozygous plant that has bitter fruit and yellow spots is crossed
with a homozygous plant that has sweet fruit and no spots. The F1 are crossed to
each other to produce the F2.
a. What will be the phenotypic ratios in the F2?
b. If an F1 plant is backcrossed with the bitter, yellow-spotted parent, what
phenotypes and proportions are expected in the offspring?
c. If an F1 plant is crossed with the sweet, unspotted parent, what phenotypes
and proportions are expected in the offspring?
Use the prompt below for the rest of the questions:
In dogs, the Agouti gene is located on chromosome 4 and encodes for a protein
required to convert yellow to brown pigment. When Agouti is non-functional, brown
pigment is not made. The alleles for Agouti are “H” (wildtype) & “h” (a hypomorph).
A second gene, MCR3, is on the X chromosome and encodes for a protein required for
the formation of yellow pigment. When MCR3 is non-functional, yellow pigment is not
made resulting in white dogs. The alleles for MCR3 are “D” (wildtype) & “d” (an
amorph). Dogs, like humans, have X and Y sex chromosomes and are diploid.
2) Write the pathway regulated by these two genes in dogs. Make sure to indicate
which gene functions at each step.
3) A male white dog mates with a yellow female dog. All male and female offspring are
yellow. What were the genotypes of the parents? Justify your answer
4) HhXdY mates with HHXDXd.
a. What are the colors of the mother and father?
b. What are all the possible genotypes of the offspring?
c. what are all the possible phenotypes and their frequencies of the offspring?
Bio340
Quiz 6 Due
April 5th by 11:59 pm
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