Question

What is the mode of action of exonuclease III?

(a) Exonuclease III acts on single stranded DNA in 3’-5’ direction

(b) Exonuclease III acts on double stranded DNA in 5’-3’ direction

(c) Exonuclease III acts on single stranded DNA in 5’-3’ direction

(d) Exonuclease III acts on double stranded DNA in 3’-5’ direction

I got this question during an online interview.

I'm obligated to ask this question of Exonucleases topic in section Basics of Genetic Engineering of Genetic Engineering

Answer 1

Correct answer is (d) Exonuclease III acts on double stranded DNA in 3’-5’ direction

To explain I would say: It is an enzyme which is having exonuclease activity in 3’-5’ direction and only on double stranded DNA. It doesn’t act on single stranded molecules.