Question

In hamsters, we can examine the genes for coat color and eye color which are linked:B = brown coat, b = white coat, G = green eyes, g = pink eyesTwo purebreeding hamsters were mated. All the F1 were brown with green eyes. F1 hamsters were mated several times with purebreeding white hamsters with pink eyes and the F2 offspring were:Brown, pink eyes – 99White, green eyes – 103Brown, green eyes – 12White, pink eyes- 11Approximately how far apart are the two genes?

Answer 1

Answer:

10.2 cM

Explanation:

Given,

pure breeding parent 1 : BBgg = brown coat and pink eyes

pure breeding parent 2 : bbGG = white coat and green eyes

BBGG X bbgg = F1 = BbGg ( All are brown with green eyes )

When F1 progeny is test crossed with white coat and pink eyes hamster:

BbGg X BbGg = F2 =

brown, pink eyes = 99 = parental

white, green eyes = 103 = parental

brown, green eyes = 12 = recombinant

white, pink eyes = 11 = recombinant

Recombination frequency =

(total number of recombinants / total progeny ) * 100

= [( 11 + 12 ) / ( 99 + 103 + 12 + 11 )] * 100 = (23/225)*100 = 0.102 * 100 = 10.2 %

1 % recombination frequency = 1 cM distance between genes

Hence, the distance between B and G gene is 10.2 cM