Question

Which one is a true statement regarding DNA polymerase used in PCR?

• A. It serves as a selectable marker.
• B. It remains active at high temperature.
• C. It is isolated from a virus.
• D. It is used to ligate introduced DNA in the recipient cell.

Answer 1

The correct option is B It remains active at high temperature.

Introduction to PCR

PCR stands for Polymerase Chain Reaction. In this process there is selective amplification of a specific region of DNA, also known as gene of interest (GoI), using a thermal cycler, DNA primers, deoxyribonucleotide triphosphates, and a thermostable DNA polymerase.

DNA polymerase used in PCR

● In the final step of PCR, a thermostable DNA Polymerase enzyme known as Taq polymerase, attaches to the DNA strands at the location of the primers.

● It adds the dNTPs (deoxyribonucleotides) one by one to the free ends of the primers, to create a complementary strand. This reaction occurs at a temperature of 72℃.

DNA polymerase used in PCR

● Taq polymerase being a thermostable polymerase remains active at such high temperatures and can conduct the extension of the primers. It is extracted from a thermophilic bacterium named Thermus aquaticus.

● It neither helps in ligating DNA strands nor does it act as a selectable marker.

Final answer
d. It remains active at high temperatures.