. Female fruit flies from a true-breeding strain with yellow body and cut wings
ID: 280258 • Letter: #
Question
. Female fruit flies from a true-breeding strain with yellow body and cut wings are mated to male fruit flies from a true breeding strain that is wild type for both body color and wings. In the F1 generation, all of the female flies are wild type for both characters while all of the male flies have yellow bodies and cut wings. The Fl males and females are intercrossed, and among 1000 male progeny the following is observed: 425 yellow body and cut wings 405 wild type body and wild type wings 90 yellow body and wild type wings 80 wild type body and cut wings Are these genes X-linked or autosomal? How far apart are they from each other?Explanation / Answer
1) Females are true breeding with yellow bodies and cut wings. Males are true breeding that is wild type for both body color and wing. In the F1 generation, all the female flies are of wild types for both body color and wings. Males of F1 generation yellow bodies and cut wings. Since there is difference is present between male and female flies in F1 generation, the trait should be linked to sex chromosomes. As both males and females share the trait, it should be present in X chromosome.
2) The distance between the two genes are calculated by finding the proportion of recombinsnts
= (90+80)/(425+405+90+80)
= 170/1000
= 17%
= 17 cM
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