23 6pts In Labrador Retrievers a breed of dog pigment color

23. (6pts) In Labrador Retrievers (a breed of dog), pigment color is influenced by two unli genes. Gene A determines the type of pigment produced and gene B affects whether or the pigment gets deposited in the hair shaft. True-breeding Brown Labrador Retrievers mated to true-breeding Yellow Labrador Retri esult in Black Labrador Retrievers. wo heterozygous (AaBb) Labrador Retrievers (black) were mated, and generated 4 litt pups each 32 pups: 17 were black; 9 were yellow; and 6 were brown.

Solution

1. The four genotype classes would be - 9 A_B_ ,3 aaB_ ,4 A_bb

2 .If we draw a punnet square for the above set AaBb x AaBb cross. rather than normal 9:3:3:1 ratio,it would be 9:3:4.There are three different phenotypes for hair colour brown, black and yellow.

3 .A_B_ black dogs ,aaB_ brown dogs, A_bb yellow

4. recessive epistasis