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•  PCR can be used to amplify small amounts of DNA

The polymerase chain reaction (PCR) is an artificial method of replicating DNA under laboratory conditions

  • The PCR technique is used to amplify large quantities of a specific sequence of DNA from an initial minute sample
  • Each reaction cycle doubles the amount of DNA – a standard PCR sequence of 30 cycles creates over 1 billion copies (230)

Stages of PCR

PCR occurs in a thermal cycler and uses variations in temperature to control the replication process via three steps:

  1. Denaturation – DNA sample is heated to separate it into two single strands (~95ºC for 1 min)
  2. Annealing – DNA primers attach to the 3’ ends of the target sequence (~55ºC for 1 min)
  3. Elongation – A heat-tolerant DNA polymerase (Taq) binds to the primer and copies the strand (~72ºC for 2 min)

Once large quantities of DNA have been created, other laboratory techniques are used to isolate and manipulate the sequences

Overview of a Polymerase Chain Reaction Cycle

PCR components