What enzyme is commonly used in PCR due to its ability to withstand high temperatures?

Taq DNA polymerase is specifically chosen for polymerase chain reaction (PCR) because of its thermal stability, which allows it to function effectively at the high temperatures required during the denaturation phase of PCR. This enzyme, derived from the thermophilic bacterium Thermus aquaticus, can withstand temperatures that can exceed 90°C, making it ideal for the cyclic heating and cooling processes in PCR.

During PCR, the mixture is subjected to high temperatures to separate the DNA strands. Many other DNA polymerases are inactivated at these temperatures, but Taq DNA polymerase remains functional, enabling it to synthesize new strands of DNA during the extension phase after the primers anneal to the single-stranded templates. This property is crucial for the amplification process, allowing researchers to generate millions of copies of a specific DNA fragment within a short period.

Other enzymes mentioned, such as standard DNA polymerases, reverse transcriptase, and RNA polymerase, do not possess the necessary thermal stability to function under the high temperatures utilized in PCR, making them unsuitable for this application.