PCR is the cloning or amplification of DNA, copies need to be made to rapidly increase the amount of DNA, this is useful if the source of DNA is small.
Firstly in a PCR reaction, DNA samples are heated to 94-96⁰C for several minutes to denature (separate into single strands) the target DNA.
The temperature is then lowered to 50-65⁰C for several minutes to let left and right primers to base pair to their complementary bases. The primers are designed to bracket the DNA region to be amplified.
Temperature is then raised again to 72⁰C for several minutes to allow Taq polymerase to attach at each priming site and synthesize a new DNA strand.
Temperature is raised to 94-96⁰C again to denature the DNA like in the beginning thus starting the process again
Why might you want to amplify minute quantities of DNA?
We need to clone DNA for sequencing, DNA-based phylogeny, or functional analysis of genes; the diagnosis of hereditary diseases; the identification of genetic fingerprints (used in forensic sciences and paternity testing); and the detection and diagnosis of infectious diseases.
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