Agha Babar Hussain, Masood Anwar, Karamat Ahmed Karamat.
PCR for HCV RNA - an introduction to the technique.
Pak J Pathol Jan ;12(2):46-7.

There are various steps involved in PCR. Denaturation of double stranded target DNA into single stranded DNA is the first step. This is followed by annealing of the primers to the sequence of interest in the single stranded DNA. The primers are custom-made short DNA fragments and are usually 20-40 nucleotide long. The DNA sequence of the primer is complementary to the target sequence. Annealing is followed by extension/lengthening of the primers. The extension of primers takes place by the help of polymerase enzyme and Deoxyribose Nucleotide Triphosphates (DNTPs). The extension results in conversion of single stranded DNA into double stranded DNA and doubling of initial number of DNA molecules. The newly formed double stranded DNA is again denatured and converted into single stranded DNA and the whole process is repeated in the form of repetitive cycles. After 25-30 cycles, one molecule of the target DNA can be amplified to produce over 100 million DNA molecules of identical size. All these steps take place at their particular temperatures which are provided in a cyclic manner through a thermocycler. The basic technique of PCR has been improved at its various steps in the form of nested PCR to get optimum results. The technique has also been modified for quantitation of amplified products to estimate the load of infectious agents. It has also been exploited to determine genotype of the infective agent in the test sample. PCR because of its flexibility and ease of performance remains the most widely used molecular technique both in research and .clinical laboratories. This is a review article.

PakMediNet -Pakistan's largest Database of Pakistani Medical Journals -