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.