Question

In a certain breed of dog, the alleles B and b determine black and brown coats respectively. However, the allele Q of a gene on a separate chromosome is epistatic to the B and b color alleles resulting in a gray coat (q has no effect on color). If animals of genotype B/b ; Q/q are intercrossed, what phenotypic ratio is expected in the progeny

Answer 1

12 gray , 3 black, 1 brown

Step-by-step explanation:

If Q allele of a gene on a separate chromosomes is epistatic to the B (black) and b (brown) color alleles, in cross between two animals with genotypes BbQq produces 12 gray coat color, 3 black coat color and 1 brown coat color animals.

BbQq x BbQq

Gray coat Gray coat

BQ Bq bQ bq

BQ BBQQ(gray) BBQq(gray) BbQQ(gray) BbQq(gray)

Bq BBQq(gray) BBqq(Black) BbQq(gray) Bbqq(Black)

bQ BbQQ(gray) BbQq(gray) bbQQ(gray) bbQq(gray)

bq BbQq(Gray) Bbqq(Black) bbQq(gray) bbqq(brown)

So the phenotypic ratio is Gray : Black : Brown

= 12 : 3 : 1