First line says \"A cross is made between an Hfr strain that is Str^s a+ b+ d+..
ID: 300870 • Letter: F
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First line says "A cross is made between an Hfr strain that is Str^s a+ b+ d+....
Part 3: Short answer (50 total points for this section d ovelos Question 3.1 (12 total points): A cross is made between an Hfr strathtser a'b'd and an F strain that is Strabd. Interrupted-mating studies show that b' enters the recipient strain last, and that the Str locus is very far away from b, so it never enters the recipient strain. The b recombinants are then tested for the presence of the a" and d' alleles. The following data were obtained a b d 326 a* b d 14 a b' d 58 400 Write the gene order of the Str, a, b, and d genes beginning with the origin of transfer. (4 points) What is the map distance between markers a and d? (4 points) What is the map distance between markers b and a? (4 points)Explanation / Answer
To determine the gene order, we have to compare a+ b+ d- with a- b+ d+. Here, the b is enter last in recipient so b will be the first in order of gene. Now if the order of gene is b d a than 4 crossover would be required to get b+ d- a and 2 cross over required to get b d+ a-. if order is bad, then 4 cross over required to get b+ a- d+ and 2 is required to b+ a+ d-. If you see recombinant frequency of a+ b+ d- is 14 where as a- b+ d+ is 2. So, the gene order is bad. As mentioned that str is far from b so sequence is
Str. b. a. d from the orgin of transfer
The order will be d. a. b. Str
Now, the map distance between a and d is calculated from a+ b+ d- recombinant frequency
That is 14 so 14/400 x 100 = 3.5% = 3.5 m.u.
Map distance between a and be is calculate from the recombinant class a- b+ d- and that is 58
58/400x 100 = 14.5% = 14.5 m.u.
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