keerti

Polymerase chain reaction ( PCR) , a technique used to make numerous copies of a specific segment of  DNA  quickly and accurately. The polymerase  chain reaction  enables investigators to obtain the large quantities of DNA that are required for various experiments and procedures in  molecular biology ,  forensic analysis ,  evolutionary  biology, and medical diagnostics. PCR was developed in 1983 by  Kary B. Mullis , an American  biochemist  who won the  Nobel Prize  for Chemistry in 1993 for his invention. Before the development of PCR, the methods used to amplify, or generate copies of,  recombinant DNA  fragments were time-consuming and labour-intensive.  PRINCIPLE PCR amplifies a specific region of a DNA strand (the DNA target). Most PCR methods amplify DNA fragments of between 0.1 and 10  kilo base pairs  (kbp) in length, although some techniques allow for amplification of fragments up to 40 kbp.The amount of amplified product is determined by the available substrates in the react