Ascospores from a cross of c $\times$ d e (all auxotrophic markers)are analyzed.If genes c and d are linked,10 map units apart,but gene e is located on a different chromosome,what proportion of ascospores is expected to be c⁺d⁺e⁺? A)about 1% B)about 2.5% C)about 5% D)about 40% E)about 50%

Question

Quizplus · Accepted Answer

Since genes c and d are linked and are 10 map units apart, the expected frequency of recombinants between those two genes is 10%. However, since gene e is located on a different chromosome, its inheritance is independent of the other two genes. Therefore, the overall frequency of the c⁺d⁺e⁺ genotype is equal to the product of the frequencies of each individual genotype: (3/4 x 1/2 x 1/2) x (1/4 x 1/2 x 1/2) x (3/4 x 1/2 x 1/2) = 0.0234 or about 2.5%.

Ascospores from a Cross of C ×\times× D E (All Auxotrophic Markers)are Analyzed

Ascospores from a Cross of C $\times$ D E (All Auxotrophic Markers)are Analyzed