In Drosophila , the genes for withered wings ( whd ), smooth abdomen ( sm ) and
ID: 312167 • Letter: I
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.
For the remainder of this problem, assume that the interference for these genes is 0.3. The number of observed double crossover progeny is 33.
C) How many offspring are expected to have the following phenotypes?
withered wings, speck body
OR
smooth abdomen
D) How many offspring are expected to have the following phenotypes?
withered wings, speck body, smooth abdomen
OR
wild type
E) How many offspring are expected to have the following phenotypes?
withered wings, smooth abdomen
OR
speck body
Explanation / Answer
C)544 as(2000-1456)/2=544/2=271
D)122 as (2000-1756)/2=244/2=122
E)573 as(2000-854)/2=1146/2=573