Polymerase chain reaction (PCR) is a method used to analyze a short sequence of DNA (or RNA) even in samples containing only minute quantities of DNA or RNA.
It is used to reproduce (amplify) selected sections of DNA or RNA in a few hours and it is so highly efficient that untold numbers of copies can be made of the DNA.
PCR has innumerable uses – for DNA fingerprinting, finding bacteria and viruses, diagnose genetic disease, etc.
PCR was discovered by a Nobel Prize winner Kary Mullis in 1983 by working for one of the first biotechnology companies California for Cetus from Emeryville.
PCR is done in three major steps (denaturation, annealing, and extension) which must be repeated for 30 to 40 cycles on an automated cycler, a device which rapidly heats and cools the test tubes containing the reaction mixture.
Reverse transcriptase-polymerase chain reaction (RT-PCR) is a method for the detection and quantitation of mRNA (messenger RNA) and it has been used to measure viral load with HIV and may also be used with other RNA viruses such as measles and mumps.