What is Polymerase Chain Reaction?

Polymerase Chain Reaction (PCR) is a method of DNA amplification. This method utilises complementary primers which target a fragment of interest within DNA. It is made up of cycles of repeated heating and cooling which amplify the target region. Each PCR cycle consists of three stages: denaturation, annealing and extension. During denaturation the reaction is heated to 95 degrees Celsius and allows for the double stranded DNA molecule to separate. At the annealing stage, the reaction is cooled down to approximately 55 degrees Celsius allowing for the primers to anneal to the target sequence. Finally, the reaction is heated up to 72 degrees Celsius for the extension stage. At this stage the thermostable Taq polymerase can copy the target sequence by incorporating complementary base pairs to the 3' end of the new DNA strand.