Editing DNA profiling (section)

===Polymerase chain reaction (PCR) analysis===
This technique was developed in 1983 by Kary Mullis. PCR is now a common and important technique used in medical and biological research labs for a variety of applications.<ref>{{Cite journal |last1=Rahman |first1=Md Tahminur |last2=Uddin |first2=Muhammed Salah |last3=Sultana |first3=Razia |last4=Moue |first4=Arumina |last5=Setu |first5=Muntahina |date=2013-02-06 |title=Polymerase Chain Reaction (PCR): A Short Review |url=https://www.banglajol.info/index.php/AKMMCJ/article/view/13682 |journal=Anwer Khan Modern Medical College Journal |language=en |volume=4 |issue=1 |pages=30–36 |doi=10.3329/akmmcj.v4i1.13682 |issn=2304-5701|doi-access=free }}</ref>

PCR, or Polymerase Chain Reaction, is a widely used molecular biology technique to amplify a specific DNA sequence.
[[File:Polymerase chain reaction.svg|thumb|Steps of polymerase chain reaction]]
Amplification is achieved by a series of three steps:

'''1- Denaturation''' : In this step, the DNA is heated to 95 '''°C''' to dissociate the hydrogen bonds between the complementary base pairs of the double-stranded DNA.

'''2-Annealing''' : During this stage the reaction is cooled to 50-65 '''°C''' . This enables the primers to attach to a specific location on the single -stranded template DNA by way of hydrogen bonding.

'''3-Extension''' : A thermostable DNA polymerase which is Taq polymerase is commonly used at this step. This is done at a temperature of 72 '''°C''' . DNA polymerase adds nucleotides in the 5'-3' direction and synthesizes the complementary strand of the DNA template .

{{Main|Polymerase chain reaction}}