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Polymerase chain reaction
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The polymerase chain reaction, which everyone calls PCR, is a fast, inexpensive technique for amplifying, that is, copying, small segments of DNA. That is why it was given a nickname that says it all: molecular photocopying.
The trick has two steps that repeat. First the sample is heated, and the heat denatures the DNA: its two strands, which normally stay locked together like the two sides of a zipper, come apart. Then an enzyme called Taq polymerase, the one that builds new DNA, steps in and, using each old strand as a template, assembles two new strands. When it finishes, there is twice as much DNA as before. And that is where the power lies: that cycle repeats dozens of times, and since each round doubles what came before, you end up with more than a billion exact copies of the original segment.
In brief
The polymerase chain reaction, or PCR, is a fast, inexpensive technique for amplifying, meaning copying, small segments of DNA; it is sometimes called molecular photocopying.
The sample is first heated so the DNA denatures and separates into two single strands; an enzyme called Taq polymerase then builds two new strands using the originals as templates.
The cycle repeats dozens of times, leaving more than a billion exact copies of the original segment.
Sources (1)
- National Human Genome Research InstitutePolymerase Chain Reaction (PCR) Fact Sheet
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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