The Polymerase Chain Reaction: Getting Started

The polymerase chain reaction (PCR) uses two oligonucleotide primers to direct the synthesis of specific sequences of DNA. One primer anneals to the coding strand of DNA and the other to the anticoding strand; the primer binding sites are typically separated by a few hundred base pairs (100–1000 bp). Repeated cycles of polymerization and denaturation lead to the exponential increase of the sequence defined by the primers. The extraordinary sensitivity and specificity of PCR have established it as a standard technique in molecular biology in the short time since it was first described (1 ).