What is PCR?

Hint: It is a polymerase chain reaction which is a three step process to make multiple copies of DNA. This three process cycle is repeated 30-40 times to produce a lot of copies of the DNA of interest.

Complete answer:
PCR is a polymerase chain reaction which was developed in 1983 by Kary Mullis and he is an American botanist who was awarded with the Nobel prize for his work.
This is a technique which is used in molecular biology in order to make multiple copies of the small sections of the DNA as because of this it is possible to make thousands to more than millions copies of DNA from just a small amount of DNA.
This technique is used in various processes like DNA sequencing, Isolation or cloning of DNA, DNA sampling, etc. It is based on DNA polymerase.
For this PCR technique there is requirement of mainly 5 things which are-
DNA template- DNA template which needs to be copied is required.
Primers- Primer is required to initiate the PCR reaction.
DNA nucleotide bases - These bases are building blocks of DNA as these are mainly required to construct the new strand of DNA. There are four bases in DNA which are A,C,G and T i.e., Adenine, Cytosine, Guanine and Thymine.
Taq polymerase enzyme- This enzyme is required in order to add in the new DNA bases.
Buffer solution- It is required to make sure that the condition is right for the reaction.
It involves three steps for this process-
1. Denaturing- DNA is double stranded and to separate these two strands denaturation is done where the DNA template is heated at 94-95 degree Celsius to separate it into two strands.
2. Annealing- When the strands get separated, then DNA primers are attached to the template DNA in this step. This step is done at 50-55 degree Celsius temperature.
3. Extending- In this step, the heat is increased to 72 degree Celsius by the help of taq polymerase a new strand of DNA is made around the both separated strands. Taq polymerase adds DNA bases.
These steps are repeated around 30-40 times in order to make so many copies of DNA.

Note: This PCR technique is mainly used to make multiple copies of DNA which involves three steps where in the first step which is denaturation, denaturation of the template strand is done in order to make these double stranded DNA strands. After this the primers are attached to each strand and then the taq polymerase enzyme is used to make a new strand of DNA.