Polymerase Chain Reaction

(c) Christopher Greneau

Check out this video clip on how PCR works!

http://school.eb.com/eb/art-16680/Specific-segments-of-DNA-are-amplified-in-a-laboratory-using?&articleTypeId=1

In 1983 a man named Kary B. Mullis discovered the Polymerase Chain Reaction (PCR). Prior to this discovery, the only methods to amplify, or generate, copies of DNA were time-consuming and labor-intensive methods. Now, with the discovery of PCR, a machine can generate billions of copies of DNA within a few hours.

PCR is a three step process. This process is repeated 25-30 times, so that thousands of copies of DNA are made.

Step One: Denaturation is the process of the separation of DNA molecules. This is accomplished by heating at 203 degrees Fahrenheit.

Step Two: The temperature is reduced to 131 degrees Fahrenheit, so that the primers can anneal to the template.

Step Three: The temperature is raised back up to 162 degrees Fahrenheit and the DNA polymerase begins adding nucleotides onto the ends of annealed primers

What this has to do with Thermus aquaticus:

    Prior to the discovery of Thermus aquaticus the DNA polymerase had to be replenished every cycle, because it was not stable at the high temperatures needed for denaturation. In 1987 this problem was solved with the discovery of a heat-stable polymerase called Taq. Taq is an enzyme which is isolated from the thermophilic bacterium Thermus aquaticus. With the discovery of Taq a whole new era in science and medicine opened up, because now DNA could be quickly replicated without heavy duty labor. The Taq polymerase led to the invention of the PCR machine, which now is widely used in research and medical diagnostics.

"The PCR process is lighting [scientists] path as they move through these projects." Susan Kelly, outreach and education coordinator from the Thermal Biology Institute at Montana State University