Answer to Question #307531 in Genetics for sarh

Question

The following pedigree analysis shows the inheritance of a recessive trait.

a. If individuals III-3 and III-8 marry, what is the probability of them having a child who phenotypically expresses the trait?

b. If individuals IV-1 and IV-10 marry, what is the probability of them having a child who phenotypically expresses the trait?

Answer 1

There are 4 out of 16 possible combinations of gametes from an SsYy x SsYy cross with the genotype of SsYy. We would therefore predict that 4/16 (or 1/4) of the offspring of the cross would be heterozygous for both traits.