Question

In Drosophila, the genes for withered wings (whd), smooth abdomen (sm) and speck body (sp) are located on chromosome 2 and are separated by the following map distances: whd ----------(30.5)----------sm-----(15.5)-----sp A female with withered wings and a smooth abdomen was mated to a male with a speck body. The resulting phenotypically wild-type females were mated with males that had the mutant phenotype for all three traits, producing 1000 offspring. Part A Calculate the number of expected double crossover progeny. Express your answer to the nearest whole number.

Answer 1

The number of expected double crossover progeny is 47.275

To the nearest whole number 47

Explanation:

Consider the provided information.

The distance between withered wings (whd) and smooth abdomen (sm) is 30.5,

That means the probability of crossover between them is 0.305.

The distance between smooth abdomen (sm) and speck body (sp) is 15.5,

That means the probability of crossover between them is 0.155

The resulting phenotypically wild-type females were mated with males that had the mutant phenotype for all three traits,

That means the expected frequency of double crossover progeny will be:

0.305×0.155 = 0.047275

It is given that they producing 1000 offspring, therefore,

0.047275×1000 = 47.275

The number of expected double crossover progeny is 47.275

To the nearest whole number 47