In gerbils the gene that specifies coat color is sexlinked a

In gerbils, the gene that specifies coat color is sex-linked and has multiple alleles, as follows: B-black, Br-brown, By-yellow, and b-albino. The allele Br is incompletely dominant over By, the combination Br By giving tan color; otherwise, dominance is in the order given - B, Br, By, b. A black gerbil mated with a yellow gerbil gave one brown male and one black female offspring.

a) what is the sex of the black parent?

b) what is the genotype of the brown offspring?

c) If the two offspring were to mate with each other, what is the probability that they will have a yellow offspring?

d) If the two offspring were to mate with each other, what is the probability that the first three female offspring will be black?

e) If the brown offspring were to mate with his mother, what is the probability that the first two offspring will be brown males?

Solution

Answer:

a). Black parent is female

(female) X^BX^Br x    (Male) X^By Y  

X^By

Y

X^B

X^B X^By (black famle)

X^B Y (black male)

X^Br

X^ByX^Br (yellow female)

X^Br Y (brown male)

b). X^Br Y = Brown male (offspring)

c). Yellow= ¼

X^Br Y (brown male) x   X^B X^By (black famle)

X^B

X^By

X^Br

X^B X^Br (Black, female)

X^Br X^By (brown female)

Y

X^B Y (Black, male)

X^By Y (yellow male)

Black : brown : yellow = 2 : 1 : 1

d). I do not know how to do answer this question

e). I do not know how to do answer this question (sorry)