Question

Which of the following statements is correct with respect to exonuclease?

(a) They only act on single stranded DNA molecules

(b) They only act on double stranded DNA molecules

(c) They remove a single nucleotide base at a time

(d) They remove nucleotide bases from the middle of a polynucleotide chain

The question was asked in an international level competition.

My doubt is from Exonucleases topic in chapter Basics of Genetic Engineering of Genetic Engineering

Answer 1

Correct choice is (c) They remove a single nucleotide base at a time

For explanation I would say: Exonuclease is responsible for removal of a single nucleotide base at a time, from the end of the polynucleotide sequence. They can act on both single and double stranded DNA molecules.