PCR takes advantage of the self-replicating nature of DNA, which allows one to amplify (replicate) DNA molecules in vitro. In this technique, double stranded DNA is heated to a temperature where the strands separate. Then, short single strands of DNA (known as primers) with sequences complimentary to the ends of the region that one wishes to amplify are allowed to assemble onto the longer template molecules. The next step is enabled by the the a special version of the polymerase enzyme. The original function of this enzyme was to faciliitate the in vivo replication of DNA in thermophilic bacteria (Thermus Aquaticus), and thus it is able to operate at the warm temperatures required for the in vitro reaction. The polymerase then catalyzes the template-directed syntheses of new double-stranded DNA molecules that are identical in sequence to the starting material. When the procedure is repeated, the molecules replicate exponentially resulting in rapid and efficient amplification of the genetic material. The reaction can be carried out automatically with a thermocycler.
History
PCR was first conceived in 1983 by Kary Mullis, a molecular biologist who received a Nobel Prize for the discovery 10 years later. PCR has enabled rapid developments in biotechnology as before its invention molecular biologists had to purify DNA from bacteria, which doesn't result in nearly as much of the specific gene that one is interested in. Automation of this reaction can be done by a thermocycler, which since its invention has found its way into nearly every molecular biology lab in the world.
