The polymerase chain reaction (PCR) is an in vitro technique, which allows the amplification of a specific deoxyribonucleic acid (DNA) region that lies between two regions of known DNA sequenc

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THE POLYMERASE CHAIN REACTION

The polymerase chain reaction (PCR) is an in vitro technique, which allows the amplification of a specific deoxyribonucleic acid (DNA) region that lies between two regions of known DNA sequence1,2. It is the most widely used target amplification technique that is found in molecular biology. This technique, which was first described by Saiki et al3 and Mullis et al4, has made it possible to detect and quantitate rare target nucleic acid sequences isolated from cell, tissue or blood samples5.

The basis of this technique is the ability of DNA polymerase to extend an oligodeoxyribonucleotide primer that is specifically hybridized to a single-stranded DNA template5. Such amplification of DNA is achieved by using oligonucleotide primers or amplimers1. These are short, single-stranded DNA molecules which are complementary to the ends of a defined sequence of DNA template1. A DNA polymerase will enable the primers to extend on single-stranded denatured DNA (template), in the presence of deoxynucleoside triphosphates (dNTPs) under suitable conditions1. New DNA strands are synthesized and bound complementary to the template strands as double-stranded DNA molecules1. Basically, PCR consists of three thermally separated steps: denaturation at 95°C to ensure complete separation