01 / The world before
Researchers had limited ways to amplify trace DNA.
02 / The discovery
Polymerase chain reaction enabled repeated copying of selected sequences.
03 / The people
Kary Mullis and decades of biochemical tool development.
04 / The obstacles
Good sampling and contamination controls are essential.
05 / The world after
PCR became a common laboratory method.
06 / Why it still matters
Diagnostics and research still use variations of it.