Question

1. (5 pts) Genes D and E are located in the Drosophila genome.
   1. DE·DE females are crossed with de·de males to produce F1 flies that are heterozygous for both traits. What gametes do each of these parents make?
2. 2. F1 females were crossed with de·de males, and 2000 flies were examined. What gametes do each of these parents make?
3. 3. What are the possible genotypes of the offspring produced from the cross in part B?
4. 4. If the genes were sorting independently (not linked), what proportion of each offspring genotype and phenotype would be expected from the cross in Part B?
5. 5. The results are depicted in the table below. Do the ratios suggest the genes linked? Explain your answer.

F2 Genotypes                         Number Observed

DE·de                                     651

de·de                                       649

De·de                                       356

dE·de                                       344

6. On the table, label which progeny are recombinant and which progeny are parental.

7. Assuming the genes are linked, how far apart are the two genes?

35 map units

2. (3 pts) You carry out an experiment using the same genes described in question 1. In a second experiment, De/De females are crossed with dE/dE males to produce F1 flies that are heterozygous for both traits. F1 females were then testcrossed with de/de males.

1. What is different about this experiment, relative to the one described in question 1?

2. What are the all the possible genotypes of the testcross offspring?

The possible genotypes are:

Ddee-50%

ddEe-50%

3. Which genotypes are parental and which are recombinant?

Is this assuming the genes are sorted independently? Because if it is I got B of Q2 wrong

Answer 1

Ans1. Gametes by DE.DE females - DE

Gametes by de.de males- de

2. Gametes produced by progeny from F1 DdEe = DE, De, dE, de

Gametes by dede males= de

3. Genotypes by cross DdEe * dede = DdEe, Ddee, ddEe, ddee

GAMETES	de
DE	DdEe
De	Ddee
dE	ddEe
de	ddee

4. Proportion of each genotype and phenotype= 1/4. Every genotype and phenotype is different.

5. No, the genes are not linked because recombinants as well as parental genotypes are formed.

6. Parental progeny = DE.de, de.de

Recombinants= De.de, dE.de

7. Distance between two genes = (no. of recombinants)*100/(total progeny) = (356+344)*100/ 651+649+356+344

= 35cM

Because of time constraints, only this question could be attempted, please post another question seperately.

THANK YOU AND HAPPY TO HELP YOU!!!