PCR

PCR in the glossary for Waldenström's macroglobulinemia

PCR (polymerase chain reaction) – A technology used to amplify fragments of DNA exponentially.

Polymerase chain reaction (PCR) amplification involves two oligonucleotide primers that flank the DNA segment to be amplified and repeated cycles of heat denaturation of the DNA, annealing of the primers to their complementary sequences, and extension of the annealed primers with DNA polymerase. The primers hybridize to opposite strands of the target sequence and since the extension products are also complementary to and capable of binding primers, each successive cycle essentially doubles the amount of DNA synthesized in the previous cycle. This results in the exponential amplification of the DNA. Almost all PCR applications employ a heat-stable DNA polymerase (such as Taq polymerase), because heat-susceptible polymerases would denature under the high temperatures of the denaturation step. There are numerous applications for PCR including genotyping, cloning, mutation detection, pathogen detection, sequencing, microarrays and forensics.¹