Question

what would happen in a PCR if the taq polymerase used was not thermostable?

Answer 1

PCR- Polymerase Chain Reaction is responsible for DNA amplification to several orders of magnitude i.e formation of million copies of a specified DNA fragment.

It involves 3 steps:

1. Denaturation by heat - DNA is subjected to more than 90 degree centigrade which leads to unwinding of the double strand into separate strands.

2. Primer Annealing - Replication of the specified DNA fragment using 20-30 base DNA primers at 40-65 degree centigrade.

3. Primer Extension - After primer annealing, taq polymerase replicates the DNA strand by binding free dNTPs. Extension starts at the 3' end of the primer at temperature above 72 degree centigrade.

taq polymerase is a thermostable enzyme which is active at high temperatures above 72 degree centigrade. thermally unstable enzymes when subjected to such high temperatures loose their structure due to denaturation and thus leads to inactivity of the enzyme. if taq polymerase was not thermostable then DNA extension will be inhibited and thus the PCR amplification will not take place.