2. a. A Drosophila male from a true-breeding stockwith scabrous eyes was mated with a female from atrue-breeding stock with javelin bristles. Both scabrous eyes and javelin bristles are autosomal recessive mutant traits. The F1 progeny all had normaleyes and bristles. F1 females from this cross weremated with males with both scabrous eyes andjavelin bristles. Write all the possible phenotypicclasses of the progeny that could be produced from the cross of the F1 females with the scabrous, javelin males, and indicate for each class whether it is arecombinant or parental type.b. The cross in part (a) yielded the following progeny:77 scabrous eyes and normal bristles; 76 wild type(normal eyes and bristles); 74 normal eyes andjavelin bristles; and 73 scabrous eyes and javelinbristles. Are the genes governing these traits likelyto be linked, or do they instead assort independently? Why?c. Suppose you mated the F1 females from the crossin part (a) to wild-type males. Why would thiscross fail to inform you whether the two genes arelinked?d. Suppose you mated females from the true-breedingstock with javelin bristles to males with scabrouseyes and javelin bristles. Why would this crossfail to inform you whether the two genes arelinked?
2. a. A Drosophila male from a true-breeding stock
with scabrous eyes was mated with a female from a
true-breeding stock with javelin bristles. Both scabrous eyes and javelin bristles are autosomal recessive mutant traits. The F1 progeny all had normal
eyes and bristles. F1 females from this cross were
mated with males with both scabrous eyes and
javelin bristles. Write all the possible phenotypic
classes of the progeny that could be produced from the cross of the F1 females with the scabrous, javelin males, and indicate for each class whether it is a
recombinant or parental type.
b. The cross in part (a) yielded the following progeny:
77 scabrous eyes and normal bristles; 76 wild type
(normal eyes and bristles); 74 normal eyes and
javelin bristles; and 73 scabrous eyes and javelin
bristles. Are the genes governing these traits likely
to be linked, or do they instead assort independently? Why?
c. Suppose you mated the F1 females from the cross
in part (a) to wild-type males. Why would this
cross fail to inform you whether the two genes are
linked?
d. Suppose you mated females from the true-breeding
stock with javelin bristles to males with scabrous
eyes and javelin bristles. Why would this cross
fail to inform you whether the two genes are
linked?
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