What technique amplifies a chosen DNA region through repeated heating and cooling cycles?

The polymerase chain reaction amplifies a chosen DNA region through repeated heating and cooling cycles.

PCR uses two short primers, free nucleotides, a DNA template, and a heat-stable DNA polymerase. Each cycle usually denatures the DNA, allows primers to anneal to complementary sequences, and extends the new strands. The target region can approximately double during each cycle, producing millions or billions of copies after many cycles.

Kary Mullis conceived PCR in 1983 while working at Cetus Corporation. The use of Taq polymerase, isolated from the heat-tolerant bacterium Thermus aquaticus, made repeated high-temperature cycles practical. Mullis received the 1993 Nobel Prize in Chemistry for the invention.

PCR is used in medical testing, forensic analysis, research, and ancient-DNA studies. It does not read the complete sequence by itself; sequencing methods are needed to determine the order of bases in the amplified product.