The three bacterial markers a,b,and c are linked,but their order is unknown.A cotransduction experiment is performed and the following results are obtained. - Markers a and b are co-transduced at a frequency of 2%.
- Markers a and c are co-transduced at a frequency of 20%.
- Markers b and c are co-transduced at a frequency of 65%.
What can be concluded about the arrangement of the three markers on the bacterial chromosome?
A)The order is a-b-c,and b is closer to a than to c.
B)The order is a-b-c,and b is closer to c than to a.
C)The order is a-c-b,and c is closer to b than to a.
D)The order is b-a-c,and a is closer to b than to c.
E)The order is b-c-a,and c is closer to a than to b.

Question

Quizplus · Accepted Answer

The higher the frequency of cotransduction, the closer the genes are to each other. Since markers b and c are co-transduced at the highest frequency (65%), they must be closest to each other. The next highest frequency is between a and c (20%), suggesting that a is further from b and c but closer to c than b is to a. Therefore, the arrangement must be a-c-b, with c closer to b than to a.

The Three Bacterial Markers A,b,and C Are Linked,but Their Order