PCR stands for polymerase chain reaction and it's a technique that's used in biochemistry and molecular biology to amplify and manipulate DNA. PCR is used in a wide range of genetic manipulations. For example PCR is used in the detection of hereditary diseases. Because PCR amplifies individual genes and parts of genes, it can make it a lot easier to sequence genes to detect mutations. Genetic fingerprinting also uses PCR, and PCR works in the same way in paternity testing, the PCR making it easier for genes to be compared. PCR is also used for genetic cloning, but not in the cloning of a whole organism like Dolly the Sheep.

A scientist called Kary Mullis, working for the Cetus Corporation, first invented the PCR technique in 1983. They patented PCR and a war broke out over the PCR patent. Some companies are still fighting over the patent for Taq PCR even now. Taq stands for Thermus aquaticus and is very commonly used, however this method of PCR is not 100% reliable as it sometimes makes mistakes when copying, because it does not have a built in proof reading mechanism. Pwo and Pfu are both polymerises that do have proof reading mechanisms but they are slower than Taq. Kary Mullis received a Nobel Prize in Chemistry for his work on inventing and developing PCR in 1993, a relatively short period of time after his first invention compared to other Novel Prizes.

There are different types of PCR used in practice: Nested PCR, Intersequence specific PCR, Litigation-mediated PCR, Inverse PCR, Quantitative PCR and Colony PCR, to name a few. All have specific uses and purposes, and are modifications of the original PCR technique, which has, as a whole, completely revolutionised our ability to genetically modify and know more about our genetic heritage.

LSL