In Drosophila, mutant individuals have a black body (due to recessive allele “b”
ID: 176571 • Letter: I
Question
In Drosophila, mutant individuals have a black body (due to recessive allele “b”), and the wild-typehas a gray body. Individuals with the recessive phenotype vestigial (vg) have wings that are crumpled andmuch shorter than wild-type. Calculate the map distance between the two genes if the follow offspringphenotypes and frequencies were obtained in a cross between a double heterozygous female and a doublehomozygous recessive male.
Offspring: gray normal 283
Gray vestigial 1294
Black normal 1418
Black vestigial 241
Explanation / Answer
phenotype
observed
Grey normal
283
recombinant
Grey vestigeal
1294
parental
Black normal
1418
parental
Black vestigeal
241
recombinant
total
3236
Total recombinant =524
% of recombination= (524 /3236) x 100
=16.19%
Hence two genes are 16.2 mu or 16.2 cM apart
phenotype
observed
Grey normal
283
recombinant
Grey vestigeal
1294
parental
Black normal
1418
parental
Black vestigeal
241
recombinant
total
3236