Question

If two successive PCRs are carried out, in which PCR there are chances of having a non-specific product?

(a) First PCR

(b) Second PCR

(c) Both the PCRs

(d) It depends on the annealing temperature

The question was posed to me in exam.

Question is taken from Modifications in PCR in section Polymerase Chain Reaction of Genetic Engineering

Answer 1

The correct answer is (a) First PCR

Easiest explanation: If two successive PCRs are carried out, there are non-specific products created in the first PCR. But there are least chances that non-specific products also have annealing sites for both the primers in the second PCR. Hence, non specific products are not generated in the second PCR.