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Tuesday, November 16, 2004

Animations of Polymerase Chain Reactions

POLYMERASE CHAIN REACTION(PCR) is a technique in which a large number of DNA molecules are produced in vitro. It starts with a single molecule, and billions of exact replications can be generated within hours. We can use PCR to amplify genomes and also to determine nucleotide sequences.
There are three steps to the process:
1) Denaturization. Exposure to extreme heat(94 degrees C) breaks weak hyrogen bonds and separates the two strands of the target DNA. The separated strands are not altered.
2) Priming. An excess of primers are added to the target DNA, then cooling to around 65 degrees C enables the double-stranded DNA to re-form. The excess of primers causes the single strands to bind to a primer rather than one another.
3) Extension. Raising the temperature to about 72 degrees C increases DNA polymerase replication, thus each strand produces more DNA.

Confused? Check out these cool animations of Polymerase Chain Reactions at work!
The Polymerase Chain Reaction
The Gene Library- PCR Animation (all cycles)

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