Describe the use of PCR and how exponential amplification can be achieved.

Polymerase chain reaction (PCR) is a technique used in molecular biology to amplify a single copy or a few copies of a segment of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence. There are several stages to PCR that result in the doubling of DNA quantity. These stages can be repeated (typically 35 times) To drastically increase the amount of DNA you have. 1) Denaturing - The DNA is heated to ~90 degress celcius the double stranded helix is unzipped and seperated 2) Annealing - Small copies of complimentary DNA (primers) stick (anneal) to the ends of each single strand at ~50 degrees for 20 seconds 3) Exstension - DNA polimerase usually Taq binds to the primers at the start, and adds dNTPs in the correct complementary order at ~72 degrees celcius.