The polymerase chain reaction (PCR) consists of three steps:
- Denaturation: separate the double helix
by heat.
- Primer annealing: single-stranded complementary DNA primers
bind to denatured DNA.
- Primer extension: DNA polymerase copies the target DNA
using a pool of nucleotides.
Each cycle doubles the original target DNA.
20 cycles yield a million-fold in vitro amplification of the target DNA.
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