Biotechnology: Principles and Processes — BIOLOGY STD 12 Science — Question

PCR: PCR means Polymerase Chain Reaction = PCR. This is a technique of gene amplification. In fact, it is like a photocopying machine. With the help of a small piece of DNA, millions of copies can be made in a short time. In this reaction, multiple copies of the useful gene are synthesized by the in vitro method using two sets of primers (chemically synthesized small oligonucleotides that are complementary to the DNA region) and the DNA polymerase enzyme. This enzyme, using genomic DNA as a template, extends the primers using the nucleotides obtained from the reaction. If the DNA replication process is repeated many times, then the DNA fragment can be amplified approximately one billion times (one billion), that is, one billion copies are formed. This continuous amplification is done by thermostable DNA polymerase (isolated from the bacterium, Thermus aquaticus). It always remains active even during denaturation of double-stranded DNA induced by high temperature. If desired, the amplified fragment can be ligated to the vector and used for further cloning.