The genes for ruby eyes (rb), tan body (t) and cut wings (ct) are all found on t

Question

The genes for ruby eyes (rb), tan body (t) and cut wings (ct) are all found on the X-chromosome of Drosophila melanogaster. All of these are recessive traits. They map in the order rb, ct, t with 15.5 map units between rb and ct and 5.5 map units between ct and t. Suppose you cross a cut wing male with a homozygous female that is both tan and has ruby eyes.

1) What will the F1 females look like?

2) Draw map of the section of the X chromosomes that has these 3 genes for the F1 females

3) Assuming you testcross your F1 females. Answer the following questions:

What progeny classes would you expect?

Give approximate numbers for each class based on a total of 2000 progeny.

Assuming the i=1 and there are no double crossovers.

Assuming the i=0 and there are the expected number of double crossovers.

Explanation / Answer

1. The F1 female will have wild type .

2. rb--- + --t / + --ct-- +

3. For answering this question, I need individual numbers of DCO and SCO.

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