The genes dumpy (dp), clot (cl), and apterous (ap) are linked on chromosome II of Drosophila. In a series of two-point mapping crosses, the following genetic distances were determined. What is the sequence of the three genes?

a. dp--ap 42
b. dp--cl 3
c. ap--cl 39

The order of genes is- dp-cl-ap

Explanation:

The genes a be mapped on chromosome on the basis of the recombination frequency as the recombination shows that is the genes are linked or not.  In genetic mapping, 1 per cent recombination frequency is considered as 1 cM or map distance.

In the given question, the three gene distance are provided on the basis of which the gene can be mapped in the following manner:

1. Take the higher value of gene distance that is 42 m.u and plot them on the line,

2. now place second-highest value on the line that is 39 m.u.

3. The gene will be arranged in the order of dp-cl-ap.

4. dp--³---cl³⁹ap.

Thus, dp-cl-ap is correct.