In Drosophila melanogaster, eyeless (ey) is a recessive trait in which the eyes
ID: 64067 • Letter: I
Question
In Drosophila melanogaster, eyeless (ey) is a recessive trait in which the eyes are tiny or absent. The ey locus is found on chromosome 4. Monosomy and trisomy for this very small chromosome are compatible with survival and fertility. A trisomic wild-type male with the genotype ey+ ey ey is crossed to an ey+ ey female. Assuming random segregation of chromosomes into gametes, determine the chromosome constitution and phenotypic ratios in the offspring.
Please provide detail explanation including how to come with gametes produced by each parent!
Explanation / Answer
A trisomic wild-type male with the genotype ey+ ey ey is crossed to an ey+ ey female
ey+ ey ey x ey+ ey
Male produces 3 gametes ey+ ey and ey
Female produces 2 gametes ey+ and ey
The offspring produced : ey+ ey+ , ey+ ey and ey ey in 1:3:2 ratio.
male/female ey+ ey ey ey+ ey+ ey+ ey+ ey ey+ ey ey ey+ ey ey ey ey ey