you want to measure the distance between two linked genes in guinea pigs (hair color and nose color). You cross two true-breeding strains with opposite phenotypes together, and then you test-cross the F1 offspring. The counts for the offspring are as followed: 512 brown hair, pink nose 85 brown hair, black nose 98 yellow hair, pink nose 505 yellow hair, black nose What is the distance between the two loci in cM

Answer: The distante between the two loci: 15.25cm

you want to measure the distance between two linked genes in guinea pigs (hair color and nose color). You cross two true breeding strains with opposite phenotypes together, and then test cross the F1 offspring. The counts for offspring are as follows: 512 brown hair, pink nose 85 brown hair, black nose 98 yellow hair, pink nose 505 yellow hair, black nose What is the distance between the two loci in CM?

According to the case we have 2 important characteristics of guinea pigs such as the color of the hair and nose, with which we generate F1

add the total number of descendants

(512 + 85 + 98 + 505) = 1200

We compare that the high frequencies which tell us about the genetics of the parents

85 + 98 = 183

so we can calculate the number of crossbred pups by making the sum

512 + 505 = 1017

crossing frequency = (total number of offspring / number of crossbred pups) x100

replacing we get:

crossover frequency = (183/1200) x100 = 15.25 cm