Editing DNA replication (section)

== Polymerase chain reaction ==
{{Main|Polymerase chain reaction}}
Researchers commonly replicate DNA ''in vitro'' using the [[polymerase chain reaction]] (PCR). PCR uses a pair of [[primer (molecular biology)|primers]] to span a target region in template DNA, and then polymerizes partner strands in each direction from these primers using a [[thermostable DNA polymerase]]. Repeating this process through multiple cycles amplifies the targeted DNA region. At the start of each cycle, the mixture of template and primers is heated, separating the newly synthesized molecule and template. Then, as the mixture cools, both of these become templates for annealing of new primers, and the polymerase extends from these. As a result, the number of copies of the target region doubles each round, [[exponential growth|increasing exponentially]].<ref name="Saiki2">{{Cite journal |display-authors=6 |vauthors=Saiki RK, Gelfand DH, Stoffel S, Scharf SJ, Higuchi R, Horn GT, Mullis KB, Erlich HA |date=January 1988 |title=Primer-directed enzymatic amplification of DNA with a thermostable DNA polymerase |journal=Science |volume=239 |issue=4839 |pages=487–491 |bibcode=1988Sci...239..487S |doi=10.1126/science.239.4839.487 |pmid=2448875}}</ref>