I really need help with part C, but I gave all the info needed: thank you! When
ID: 213239 • Letter: I
Question
I really need help with part C, but I gave all the info needed: thank you!
When a female fruit fly with forked bristles is mated to a male with wild type bristles, all the F1 males have forked bristles and the F1 females have wild type bristles. When a male with forked bristles is mated to a female with wild type bristles, all the F1 offspring have wild type bristles. You can assume that the parent generation males and females are true-breeding (none of the parent flies are heterozygous.)
a) Explain the observed pattern of inheritance. Specifically, state whether the forked bristle trait is dominant or recessive and whether it is x-linked or on an autosome.
b) Again, using the format for Drosophila genes, assign genotypes to the two parent crosses and their F1 offspring.
Cross 1 forked bristle females x wild type males: F1 offspring:
Cross 2 forked bristle males x wild type females: F1 offspring:
C) What F2 phenotypes and ratios are expected if the F1 offspring of Cross 1 are mated with each other? Show your work.
Explanation / Answer
From the given data,
Forked bristle is an X-linked recessive trait.
C.
WT = X+
Mutant = Xfr
Parental cross 1: XfrXfr X X+Y
F1 progeny: X+Xfr XfrY
F1 selfing: X+Xfr X XfrY
Gametes: (X+) (Xfr) X (Xfr) (Y)
F2 porgeny: X+Xfr XfrXfr X+Y XfrY
X+Xfr = WT female
XfrXfr = Forked female
X+Y = WT male
XfrY = Forked male