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The key to PCR

To carry out PCR, scientists use a machine that heats the DNA to 95 degrees centigrade. At this temperature, the DNA unzips into two separate strands, which the builder enzyme uses to make more DNA copies. Most enzymes are destroyed at this temperature, so the key to PCR is to use a super heat-resistant type of the builder enzyme. It is found in bacteria that live in hot water springs, and so can survive constant high temperatures.

Hot-water spring in Rotorua, New Zealand.
Hot-water spring in Rotorua, New Zealand.
Nicky Lewis

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