George has discovered a new wing shape in Drosophila and decided to call this spirally rotated wing "twist". To find out if this gene is on chromosome 3 he did a testcross of a heterozygous female to a male that is ebony (e, chromosome 3), scarlet (st, chromosome 3), and twist (tw). The following progeny resulted

+ + + 105

st tw + 301

+ tw + 107

st + + 307

+ + e 305

st + e 112

+ tw e 300

st tw e 99

a. (2 pts) Diagram this cross (using the correct gene order and coupling):

b. (1 pt) Identify the progeny as Parentals (P), recombinant (R), region 1 crossover (R1), region 2 crossover (R2), or double crossover (dco) as appropriate (you may not use all of these designations!)

c. (1 pt) Determine the map distance between all linked genes.

d. (2 pts) What gamete types would George have seen if he crossed a heterozygous male to a homozygous recessive female? Use the inverse of the cross in part a as an example and be specific.

(2 pts) The original question asked Rupert to determine if hot tamale was linked to the other two genes. In part d, you showed the gametes that would be produced by the male if hot tamale were unlinked. What gamete types would be produced if all three genes were linked and we crossed a heterozygous male to a homozygous recessive female. Would Rupert have been able to determine the linkage of hot tamale? Explain. Be Specific.