Kary Mullis (Nobel 1993) developed the Polymerase Chain Reaction (PCR) to amplify the quantity of target DNA in vitro.
  1. The target DNA is denatured into single strands.

  2. Each strand is annealed to a short, complementary primer.

  3. DNA polymerase and nucleotides extend the primers, using the single-stranded DNA as a template.
After one cycle of amplification, the amount of target DNA has been doubled.