Question

1. (10 points) You have a strain of fruit flies that are black in colour (b) instead of the usual tan, have shortened wings (sw) relative to wild type, and pinkish eyes (p) instead of red. You cross b. sw. p females to wild type males and all the F1 are wild type.

Then you cross the F1 females to males from the original strain – b. sw. p. You obtain the following number and phenotypes of F2:

b sw p : 422

b⁺ sw⁺ p⁺: 403

b sw⁺ p: 63

b⁺ sw p⁺: 52

b sw p⁺: 31

b⁺sw⁺ p: 24

b⁺ sw p : 3

b sw⁺ p⁺: 2

a) Determine the correct gene order and explain how you know. (1 point)

b) Calculate map distances between all three pairs of genes, if appropriate (6 points)

c) Draw a map showing the arrangement of the genes (1 point)

d) Calculate the interference if any, and explain in one or two sentences what interference is (use your own words) (2 points)