Question

Many copies of a specific gene of interest are required to study the detailed sequencing of bases in it. Name and explain the process that can help in developing large number of copies of this gene of interest.

Answer 1

Polymerase Chain reaction (PCR).

PCR is carried out in the following three steps:

(a) Denaturation

— The double-stranded DNA is denatured by subjecting it to high temperature of 95°C for 15 seconds. Each separated single stranded strand now acts as template for DNA synthesis.

(b) Annealing

— Two sets of primers are added which anneal to the 3′ end of each separated strand.

— Primers act as initiators of replication

(c) Extension

— DNA polymerase extends the primers by adding nucleotides complementary to the template provided in the reaction.

— A thermostable DNA polymerase (Taq polymerase) is used in the reaction which can tolerate the high temperature of the reaction.

— All these steps are repeated many times to obtain several copies of desired DNA.