The dominant allele H reduces the number of bodybristles in fruit flies, giving rise to a hairless phenotype. In the homozygous condition, H is lethal. Thedominant allele S has no effect on bristle number except in the presence of H, in which case a single S allele suppresses the hairless phenotype, thus restoringthe bristles. However, S is also lethal in homozygotes.a. What ratio of flies with normal bristles to hairlessindividuals would we find in the live progeny of across between two normal flies both carrying theH allele in the suppressed condition?b. When the hairless progeny of the previous cross arecrossed with one of the parental normal flies frompart (a) (meaning a fly that carries H in the suppressed condition), what phenotypic ratio wouldyou expect to find among their live progeny?
The dominant allele H reduces the number of body
bristles in fruit flies, giving rise to a hairless
dominant allele S has no effect on bristle number except in the presence of H, in which case a single S allele suppresses the hairless phenotype, thus restoring
the bristles. However, S is also lethal in homozygotes.
a. What ratio of flies with normal bristles to hairless
individuals would we find in the live progeny of a
cross between two normal flies both carrying the
H allele in the suppressed condition?
b. When the hairless progeny of the previous cross are
crossed with one of the parental normal flies from
part (a) (meaning a fly that carries H in the suppressed condition), what phenotypic ratio would
you expect to find among their live progeny?
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