Question

I answered part a, not sure if its correct tho. I need someone to look it over and tell me if it's correct and answer part b.

The agouti locus in mice has three alleles: a is recessive and confers a black coat, A is dominant to a and confers an agouti coat, and A^Y is dominant to both and confers a yellow coat. A^Y is also a recessive lethal. In addition, the independently assorting c allele is recessive (to C) and prevents the mice from making any fur pigments at all, resulting in albinos.

(a) Two mice are crossed, and produce offspring in a ratio of 3 albino : 2 yellow : 1 black. What are the genotypes and phenotypes of the parent mice?

AY(yellow)(recessice lethal) > A(agouti) > a(black) C > c(albino)

Offspring ratio:

3 albino cc

2 yellow AY

1 black aa

Genotypes and phenotypes of the parent mice:

Cc AYa -------> yellow coat

Cc aa --------> black coat

(b) When AACC agouti mice are crossed to aacc albino mice, the progeny are all agouti. When these F1 mice are testcrossed, they produce progeny in a ratio of 1 agouti : 2 albino : 1 black. What would be the phenotypic ratio among the progeny if the F1 mice were crossed to each other instead?

Answer 1

answer 1-

(a)yes ,your answer is correct.

(b) coat colour in mice is influenced by two loci , A and C. when AACC agounti mice are crossed too aacc Albino mice, the progeny are all agounti .when there F1 mice are crossed together, they produce progeny in a ratio of

9 agounti : 4 Albino :3 black.

(C gene is epistatic to A gene)