Question

The extension step of PCR where DNA polymerase gets into action happens at ${72}^{\circ }C.$ This is a contrast to what we have learnt where enzymes are said to be functioning at optimum temperature range of ${35}^{\circ }to{40}^{\circ }C$. Why is it so?

• A. DNA polymerase is active at low pH and high temperature
• B. While ${36}^{\circ }to{40}^{\circ }C$ is the optimum temperature range, ${72}^{\circ }C$ is a special sweet spot for most enzymes to work
• C. DNA polymerase used in PCR is obtained from a bacteria that thrives in hot springs
• D. The temperature has no role to play in this process.

Answer 1

The correct option is C DNA polymerase used in PCR is obtained from a bacteria that thrives in hot springs

DNA polymerase enzyme used in the PCR is obtained from bacteria that is found in thermal vents and hot springs. They thrive in such high temperatures and hence${72}^{\circ }C.$ is the optimum temperature for their enzymes to work at. In fact, the high temperatures used to denature DNA which usually ranges from $95-{100}^{\circ }C$ also does not denature this enzyme.