The PCR12 (Polymerase Chain Reaction) is an in vitro method for the enzymatic synthesis of specific DNA sequences, using two oligonucleotide primers that hybridise to opposite strands and flank the region of interest in the target DNA. A repetitive series of cycles involving template denaturation, primer annealing, and the extension of the annealed primers by DNA polymerase results in the exponential accumulation of a specific fragment whose termini are defined by the 5’ ends of the primers. Because the primer extension products synthesised in one cycle can serve as a template in the next, the number of target DNA copies approximately doubles at every cycle. Thus, 20 cycles of PCR yields about a million-fold (220) amplification. This method, which was invented by Kary Mullis [120, 121] was originally applied by a group in the Human Genetics Department at Cetus to the amplification of human β-globin DNA and to the prenatal diagnosis of sickle-cell anemia [122, 123, 124].
© 2001 Alexander Binder