Polymerase Chain Reaction (PCR).

A DNA sample can be copied many times (amplified) in vitro in a 3-step cycle.

  1. Denaturation:
    Heating the DNA to separate the double-stranded molecule into single strands.

  2. Annealing:
    Cool the mixture to allow complementary primers to hydrogen-bond to the single strands.

  3. Extension:
    Add DNA polymerase and nucleotides to replicate each strand.