Question

Which of the following statement is incorrect for the synthesis of the second strand?

(a) The oligonucleotide is acting as a primer for the synthesis of the second strand

(b) DNA polymerase and dNTPs are added for synthesis

(c) The polymerase should have 5’-3’ exonuclease activity

(d) A polymerase having 5’-3’ exonuclease activity would degrade the primer that carries the mutant sequence

I had been asked this question in class test.

The above asked question is from Mutagenesis without PCR in portion Modifications and Mutagenesis of Genetic Engineering

Answer 1

Correct answer is (c) The polymerase should have 5’-3’ exonuclease activity

For explanation: The oligonucleotide is acting as a primer for synthesis of the second strand. DNA polymerase and dNTPs are added for synthesis and the polymerase should not have 5’-3’ exonuclease activity. If the polymerase is having exonuclease activity it would degrade the primer that carries the mutant sequence and the mutated portion is replaced by template DNA.