The PCR (polymerase chain reaction) is an extremely simple as immensely powerful methods. It permits enormous amplification of any particular sequence of DNA gives which short sequences either side of it are known. . A polymerase chain reaction have the goal double-stranded DNA, two primers which hybridize to flanking sequences on opposing strands of the goal, all four deoxyribonucleoside triphosphates and a DNA polymerase.