Question

Which of the following nucleotides should be there at 3’ end?

(a) Any of A, T, G or C will work out

(b) Either A or T

(c) Either G or C

(d) Specifically G

I had been asked this question in examination.

Question is from Primers in portion Polymerase Chain Reaction of Genetic Engineering

Answer 1

The correct option is (c) Either G or C

Best explanation: At 3’ end, either G or C should be present. It is so because; these form three hydrogen bonds and thus are stronger. Whereas, A and T form only two hydrogen bonds and thus are comparatively less strong than G or C.