A yeast strain has the genotype ADE2ade2 TRP2trp2 ura3ura3 F

A yeast strain has the genotype ADE2/ade2 TRP2/trp2 ura3/ura3. Following sporulation, what percentage of the colonies would be Ade+ Ura-?

50%

Solution

Here both the genotypes of parents are ADE2 , TRP2, ura3 x ade 2, trp2, ura3 Following sporulation , the ascus of tetrads will be 75% ADE2+, ura3- because both genotypes contain ura3-. Hence the answer must be option D . Rest of the spores will be ade2-, ura3-.