Question

What are the possibilities which can occur until the temperature has reached for primer annealing?

(a) Extension doesn’t starts until the appropriate temperature is reached

(b) Extension may start even when the temperature is low

(c) At low temperature, there is specific annealing of primer taking place

(d) There are more specific products which are generated

The question was posed to me at a job interview.

I would like to ask this question from Modifications in PCR topic in chapter Polymerase Chain Reaction of Genetic Engineering

Answer 1

The correct choice is (b) Extension may start even when the temperature is low

Explanation: Until the temperature has reached for primer annealing there are chances of extension by polymerase. It is so because at low temperatures primer can anneal in a non specific manner and thus non specific products are generated.