Polymerase Chain Reaction (PCR): Basic Principle

Polymerase chain reaction (PCR) is a primer mediated enzymatic amplification of specifically cloned or genomic DNA sequences. PCR process was invented by Kary Mullis and it has been automated for routine use in laboratories worldwide. The main purpose of the PCR process is to amplify template DNA using thermostable DNA polymerase enzyme which catalyzes the buffered reaction in which an excess of an oligonucleotide primer pair and four deoxynucleoside triphosphates (dNTPs) are used to make millions of copies of the target sequence.

PCR Components

The Polymerase Chain Reaction (PCR) created a revolution in molecular biology research and its applications. PCR is an in vitro method that enzymatically amplifies specific DNA sequences using oligonucleotide primers that flank the region of interest in the target DNA. The principle involves a repetitive series of cycles each of which consist of template denaturation, primer annealing, and extension of the annealed primers by a DNA polymerase to create the exponential accumulation of a specific fragment whose ends are determined by the 5’ ends of the primers. The PCR is so named because it involves a polymerase and the products synthesized in each cycle can serve as templates in the next so the number of DNA copies approximately doubles at every cycle to create a chain reaction similar to the principles in a nuclear reactor.