Homework SourseRecall that in Drosophila melanogaster the mutation white bl
Recall that in Drosophila melanogaster the mutation white blocks the accumulation of ____/16 both eye pigments (causing white eyes), while the mutation vermillion blocks production of the brown pigment (causing bright red eyes). These mutations are both X-linked recessive, and are separated by 31.5 m.u. You perform a parental cross, self the F1, and then score the F2. Given the F2 results presented below, which of these crosses is most likely to be the parental cross from your experiment (circle one). Show X2 tests to support your answer. You do not necessarily need to show your cross & Punnett square, but providing these might earn you part marks for an incorrect answer.
Solution
The 4th option is correct.
Female ++ vv and male w0 +0 will cross and form the male and female progenies:
Cross between ++ vv and w0 +0 [0 represents here absence of X chromosome]
Gametes [parents]
w +
0 0
+v
w+ v+ [female]
0+ 0v [male]
The above table is for F1 progenies, now self cross:
+w +v female x 0w 0+ male
Gametes [F1]
0 0 [all progenies will male]
+ v [all progenies will female]
+ +
+0 +0 wild
++ v+ wild
+ v
+0 v0 red
++ vv red
w +
0w +0 white
+w +v wild
w v
0w 0v white red
+w vv red
| Gametes [parents] | w + | 0 0 |
| +v | w+ v+ [female] | 0+ 0v [male] |
