Elongated and Five are two genes in a housefly that are 24 centiMorgans (cM; map units) apart.The E allele of Elongated produces elongated wings, and the e allele produces small wings (E is dominant).The F allele produces five stripes on the back of the fly, and the f allele produces four stripes (F is dominant).In a cross of EeFf *eeff, what proportion of the offspring should have elongated wings and five stripes?
A) 0 percent
B) 12 percent
C) 24 percent
D) 38 percent
E) 76 percent

Question

Quizplus · Accepted Answer

Given that the genes are 24 cM apart, this indicates a 24% recombination frequency. In a cross between EeFf (heterozygous for both traits) and eeff (homozygous recessive for both traits), the offspring with elongated wings and five stripes (EF phenotype) can result from non-recombinant gametes (EF from EeFf parent) and recombinant gametes where recombination between E and F alleles occurred (also EF but from the eF or Ef gametes due to crossing over). The probability of non-recombinant EF gametes is 38% because the recombination frequency is 24%, leaving 76% of gametes as non-recombinant, of which half (38%) will be EF.

Elongated and Five Are Two Genes in a Housefly That