IndexWhat is PCR?ProcedureImportance of PCRWhat is PCR?Polymerase Chain Reaction or PCR is the in vitro technique for the synthesis of DNA or we can say that it is an in vitro DNA replication procedure. This technique is generally used in the case of molecular biology for the amplification of a single copy or multiple copies of DNA segments. After the completion of this procedure, thousands or millions of copies of that particular DNA segment are generated from the very few DNA copies. This PCR technique has an elegant simplicity. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original assay Components required in PCR: DNA template containing the target region. Two DNA primers. Synthetic oligonucleotides (primers, are prepared) should be complementary to sequences on opposite strands of the target DNA at positions that define the ends of the segment to be replicated. These primers basically serve as replication primers. A DNA polymerase enzyme. Primers are extended by this enzyme and polymerize the new DNA strand. In PCR, since a high temperature is required, thermophilic DNA polymerases are used to polymerize new DNA strands. Such as Taq DNA polymerase, Deep vent R DNA polymerase. Deoxynucleoside triphosphates or dNTPs (dATP, dGTP, dCTP and dTTP). A buffer solution to maintain the appropriate chemical environment. This is necessary for optimal enzymatic activity of the polymerase and its stability. Mg2+, a divalent cation. Procedure Thermal cycling is involved in this polymerase chain reaction. This thermal cycle consists of repeated cycles of heating and cooling the reaction for DNA fusion and enzymatic replication. It sets up a chain reaction movement where exponential amplification of the DNA template occurs. The isolated DNA containing the segment to be replicated is first heated briefly to denature it. After heating it, it is then cooled in the presence of a large excess of synthetic oligonucleotide primers. Subsequently, 4 dNTPs are added together with Taq DNA polymerase and the primed DNA segment is selectively replicated in vitro. The heating, cooling, and replication cycle is repeated 25 to 30 times within a few hours in an automated process. The three fundamental phases of PCR are: Denaturation (94-98°C); Annealing (50-65°C) and extension (72°C). The whole process can be described through the following diagram. Please note: this is just an example. Get a custom paper from our expert writers now. Get a Custom Essay Importance of PCR This powerful technique is used in case of (i) medical diagnosis; (ii) Forensic medicine and (iii) Studies on molecular evolution. In medicine, PCR can provide valuable diagnostic information. Bacteria and viruses can be easily detected with the use of specific primers. For example, some tumors are detected early with the promising PCR method. Mutations in some growth control genes (ras genes) can also be identified by PCR. genetic testing, tissue typing, identification of oncogenes, etc. Besides all these, PCR is used as an indispensable tool in forensic sciences, especially in DNA fingerprinting, genetic mapping, genetic testing, tissue typing, etc...