Question

Which of the following is a neutral mutation?

(a) Replacement of a Glu by Val

(b) Replacement of AAA by UAA

(c) Replacement of Lys by Arg

(d) Replacement of Thr by Tyr

I had been asked this question during a job interview.

This intriguing question originated from DNA Mutation in division DNA Mutation, DNA Repair, Transposable Elements of Cytogenetics

Answer 1

Right choice is (c) Replacement of Lys by Arg

For explanation I would say: Lys and Arg are both basic amino acid of similar size, thus the mutation of one with another doesn’t have much effect on the final protein structure or function. On the other hand, option b is a nonsense mutation, and a and d are missense mutation.