PCR (polymerase chain reaction) is a technique in which cycles of denaturation, annealing with primer, and extension with DNA polymerase, are used to amplify the number of copies of a target DNA sequence by more than 106 times in a few hours. American molecular biologist Kary Mullis developed the idea of PCR in the 1970s. For his ingenious invention, he was awarded the 1993 Nobel Prize in physiology or medicine.

The extraction of DNA polymerase from thermophilic bacteria allowed for major advances in PCR technology.

PCR amplification of DNA is like any DNA replication by DNA polymerase in vivo (in living cells). The difference is that PCR produces DNA in a test tube. For a PCR to happen, four components are necessary: template, primer, deoxyribonecleotides (adenine, thymine, cytosine, guanine), and DNA polymerase. In addition, part of the sequence of the targeted DNA has to...