Name: Genetic Engineering
Uploaded: 2019-07-19
Duration: 6 min 20 s
Description: Genetic engineering is using technology to modify and manipulate an organism's genes. Learn more about genetic engineering and its process in the video.

Question

What is Polymerase Chain Reaction (PCR)? Explain in detail the various steps involved in PCR.

Accepted Answer

PCR or polymerase chain reaction is a technique used for the amplification of a small segment of DNA. It was discovered by Kary B Mullis in 1983. The reaction is carried out in a thermal cycler having a thermal cycling programme. It includes three steps: denaturation, primer annealing and extension. The target gene is put along with other substrates in the thermocycler. The DNA fragment becomes double at the end of the first cycle and quadruples after the second cycle and so on. In this process, no host cell is used as the supporting system.

The following are the steps involved in PCR:

Denaturation: The first step consists of the breakdown of the bonds present in between the double-stranded DNA to make it single stranded. The bonds are broken down by an increase in the temperature to about 94⁰C.

Annealing: The next step is the addition of the primers to the ends of the DNA strand. The temperature is then decreased to a certain extent (40⁰ – 60⁰C) for the primers to attach.

Extension: Third step results in the expansion of the primers by the addition of nucleotide base pairs complementary to the template strand. This results in the amplification of the molecule of DNA. A thermostable DNA polymerase is used for such repeated amplification. It is isolated from a bacterium found in hot springs, Thermus aquaticus which remain active during the high temperature induced for denaturation of
double-stranded DNA.

What is Polymerase Chain Reaction (PCR)? Explain in detail the various steps involved in PCR.

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