Genes A , B , and C are linked on a chromosome and found in the order A-B-C. Gen

Question

Genes A, B, and C are linked on a chromosome and found in the order A-B-C. Genes A and Brecombine with a frequency of 5%, and genes Band C recombine at a frequency of 23%. For the cross a +b +c /abc+ × abc / abc, predict the frequency of progeny. Assume interference is zero.

A. Predict the frequency of a+b+c progeny.

B. Predict the frequency of abc+progeny.

C. Predict the frequency of a+bc+progeny.

D. Predict the frequency of ab+c progeny.

E. Predict the frequency of a+b+c+ progeny

F. Predict the frequency of abc progeny.

G. Predict the frequency of a+bc progeny.

H. Predict the frequency of ab+c+progeny.

Explanation / Answer

Needs no recombination,

So (1-0.05) (1-0.23) = 0.721

Parent would donate half the time so,

0.721/2 = 0.36

2. abc+ progeny

Another possibility of parent one, no recombination is required so, again 0.36

3. a+bc+ progeny

would require crossover between a and b, but no crossover in b and c

(0.05)(1-0.23) = 0.0385

This would be donated half of the time so, 0.038/2 = 0.019

4. ab+c progeny

it is a single recombination product justlike 3 so the answer would be the same 0.019

5. a+b+c+ progeny

no recombiantion between ab and recombiantion between b, c

(1-0.05)(0.23)1/2= 0.218/2 = 0.109

6. abc progeny

same recombination as 5, so the answer would be 0.109

7. a+bc progeny

double recombination is required for this progeny

(0.05) (0.23) X ½ = 0.011/2 = 0.0057

8. ab+c+

it is a double recombination like 7 so the answer would be 0.0057

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