Polymerase chain reaction

Commonly abbreviated as PCR, a means of making copies of a targeted sequence of DNA.

A cycle in which a template strand of nucleic acid and one or more shorter strands of nucleic acid known as primers is alternately heated and cooled in the presence of excess nucleoside triphosphate molecules and polymerase. During the cooler part of the cycle, the polymerase extends the primer by the addition to the primer of free nucleotide from the excess nucleoside triphosphate pool. In the warmer part of the cycle, the orginal template molecule and the newly-made copy dissociate.

Subsequently, additional copies are made during the cool phase and then freed from their template strands during the warm phase, allowing the production of exponentially more copies to be produced as the temperature is cycled.

Kary Mullis is credited with the invention of PCR, for which he was awarded a Nobel Prize.

PCR is a widely-used technique in molecular biology, relying on several fundamental principles and properties of biochemistry.