In rats, the P gene allele for pigmentation (P) is dominant to the allele for albinism (p) . The B gene allele for black pigmentation (B) is dominant to the allele for cream pigmentation (b) . The pp homozygous recessive genotype is epistatic to any allele combination at gene B.
-Predict the phenotypic ratio of the F₂ progeny of a parental cross between a pure-breeding black rat and an albino that is also homozygous for cream.

Question

Quizplus · Accepted Answer

The P gene is epistatic to the B gene, meaning that if the rat is homozygous recessive pp, it will be albino regardless of the B gene alleles. The cross results in a 9:3:4 ratio, where 9 are black (P_B_), 3 are cream (P_bb), and 4 are albino (pp__).

In Rats, the P Gene Allele for Pigmentation (P) Is