Polymerase Chain Reaction (PCR)

PCR: It is a mechanism or technique through which genetic material gets duplicated in millions and billions of copies.

In this mechanism certain things are required which are:


1.Thermal Cycler(machines for temperature cycles)

2.DNA segment to be duplicated

3.Primers(RNA pieces required for attachment and processing of polymerase enzyme without which enzyme can not bind to the DNA segment)

4.DNA Taq polymerase(A heat resistant enzyme taken from Thermus Aquaticus bacteria)

5. Nucleotide bases This process consists of 3 phases with help of thermal cycler and this cycler repeats its cycles in that 3 phases multiple times

These phases are;

i Denaturation(separation of DNA segments)

ii annealings (Combining of primer to DNA)

iii extensions (formation of polynucleotide chain)


All material is taken into a single tube which will be placed in the thermal cycler.

First of all, Temperature is maintained at high levels

1.DNA strands get separated due to higher temperature(100°C) Then Temperature is lowered down

2. The primers get attached to the separated DNA segments Finally temperature again raised

3.this helps DNA Taq polymerase(heat resistant enzyme) to bind the primer and make a polynucleotide chain with the help of free nucleotides.

The resultant copies will be cycled again and again and will produce many duplicates of its own

in this way, we can make multiple copies of the DNA segment in a very short duration of time

PCR is used for




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