Currently, there are hundreds of different types of PCR are being used in different laboratories but the basic principle remains same. The overall process of PCR can be summarized as follows. 1) Mixture of all constituents of PCR like dNTPs, Primers (forward and reverse), Buffer and template DNA will be mixed in desired concentration. 2) The first step is amplification, where the temperature is set at 94C for 2-5 minutes for denaturation of double stranded DNA, a process called initial denaturation, 3) After initial denaturation, sample is kept for 30 sec at 94C for further denaturation, 4) After denaturation temperature is brought down to 55-60C for 30sec to allow annealing of primer with specific DNA site called annealing temperature. 5) The temperature is now brought up to the 72C for polymerase to start new DNA synthesis using primer as starting material. 6) After extension, the cycles are repeated for almost 30 times to get 230 copy of initial DNA template. Finally, after 3 cycle extension is be performed at 72C for 5 min to complete any unamplified reaction. Figure 1 shows steps involves in PCR.
Development of PCR and identification of DNA as signature molecules for individual leads to introduction of DNA based technique for establishment of parental relation and subsequently for crime and criminal detection. ...Show more