Question

The recombination frequency between the genes a & c is 5%, b & c is 15%, b & d is 9%, a & b is 20%, c & d is 24% and a & d is 29%. What will be the sequence of these genes on a linear chromosome?

• A. a, d, b, c
• B. d, b, a, c
• C. a, b, c, d
• D. a, c, b, d

Answer 1

Answer: (D)

a, c, b, d

Answer 2

The frequency of recombination between gene pairs on the same chromosome can be used to measure the distance between genes. The distance between two genes is equal to this recombination frequency. If genes are located on the same chromosome, some genes can be very tightly linked hence showed very low recombination and low recombination frequency. If genes are loosely linked, they show higher recombination (high recombination frequency). As the recombination frequency is smallest in case of a and c, it means they are closely located to each other (linked genes). Recombination frequency of a and c is slightly higher but they can also be linked. The recombination frequency of a and d is highest hence the chances are more for these two genes to be located far apart. The correct sequence will be a-c-b-d.