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POLYMERASE CHAIN REACTION (PCR)
Introduction
Polymerase Chain Reaction (PCR) is a molecular biology technique that allows scientists to "amplify" (produce
millions of copies of a) specific DNA sequence or fragment in the lab in a time span of a few hours.
The technique has been applied to a broad range of molecular genetics research areas and is regularly used in
fields ranging from molecular evolution to forensic crime scene investigation to the diagnosis of hereditary
disease in humans.
Small Miracle
DNA (deoxyribonucleic acid) is the molecule that contains the encoded instructions representing the genetic
blueprint of all cellular life. It is the universal molecule encoding such instructions throughout the living
world. At the same time, the specific instructions encoded in any individual person's DNA are unique to that
individual.
Despite the obvious central importance of DNA in living systems, understanding of how the molecule functions has
been slow to emerge. In 1983 scientist Kary Mullis came up with an elegant solution to many of the longstanding barriers in
genetics research by developing the technique known as the polymerase chain reaction (PCR). PCR uses a combination
of specified heating/cooling cycles and a specialized heat-tolerant nucleotide assembly enzyme to produce millions
of copies of a specific DNA sequence in a very short time.
Mullis may be equally well known in scientific circles for his eccentricities (he is an avid surfer, has admitted
to using hallucinogenic drugs, and contends he may have once been abducted by aliens) as for the development of
PCR. Nevertheless, his impact on the genetics field would be difficult to overstate. As repeated references to PCR
throughout this website will attest, the technique is a foundation of modern genetics research. PCR is also
responsible for enabling forensic crime scene investigators to identify DNA samples (Kary Mullis was even on the
list of expert witnesses for the O.J. Simpson trial, though never called to the stand).
Dr. Mullis was awarded the Nobel Prize in Chemistry for this work in 1993.
Shockwave Tutorial
For a more detailed overview of the PCR process and variations on the basic technique, select the Shockwave
multimedia applet below.
 PCR Basics Tutorial
In order to view Shockwave media files you should have the most current Shockwave Player browser plug-ins installed on your computer. These can be
downloaded for free by clicking the button below.
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