Question

The enzyme used in polymerase chain reaction (PCR) is
A) Taq polymerase
B) RNA polymerase
C) Ribonuclease
D) Endonuclease

Answer 1

Hint:Taq DNA polymerase is the most common enzyme used for PCR amplification. This enzyme is extremely heat resistant with a half-life of 40 minutes at 95°C.

Complete answer:
First, we will learn what is polymerase chain reaction process-
Polymerase chain reaction is a technique which is mainly used to amplify a DNA segment. It was given by Kary Mullis. The process includes taking the sample DNA strand and denaturing it by heating at the temperature of 95oC. Each strand of the DNA acts as a template for the new strand. The primers are annealed at 55oC to all the template. In the third step, the temperature is raised to about 72oC. The key ingredients of polymerase chain reaction are Taq polymerase which is a DNA polymerase enzyme that makes new DNA strand from the isolated DNA. It is isolated from bacterium (the reason of the enzyme being called “Taq” polymerase) is Thermus acquaticus.
Now, we will discuss about the types of enzymes listed.
1) Taq polymerase begins adding nucleotides onto the ends of the annealed primers.
2) RNA polymerase species transcribes all types of RNA. The enzyme includes four different subunit types. The σ subunit can dissociate from the rest of the complex, and thusjust left with the the core enzyme. The complete enzyme with σ is termed the RNA polymerase holoenzyme.
3) Ribonuclease is a type of nuclease that catalyzes the degradation of RNA into smaller components. They can be divided into endoribonucleases and exoribonucleases.
4) Endonucleases are the types of enzymes that break the phosphodiester bond within a polynucleotide chain. Many of the endonucleases cleave the bonds only at specific nucleotide sequences.

Hence, the correct answer is option A (Taq polymerase).

Note:Taq polymerase does not have 3′–5′ proof-reading activity. At temperatures above 90 °C, Taq shows very little or no activity at all, but the enzyme itself does not get denatured and remains intact.