Polymerase Chain Reaction
PCR or the Polymerase Chain Reaction is a technique, which is widely used in various scientific fields including molecular biology, diagnostics, genetics, forensic science, and paternity testing among others. The DNA polymerase is an enzyme, which is used for in vitro DNA replication. The original DNA molecule is replicated by DNA polymerase enzyme and it doubles the number of DNA molecules. A second cycle of replication starts where each of the DNA molecules is replicated again. These cycles are called chain reactions and millions of copies of DNA are produced from a single piece of DNA.
Three major steps are involved in the PCR process: denaturation, annealing (joining), and extension. These steps are repeated for almost 30-40 cycles in an automated cycler. The machine heats and cools the test tubes present in the reaction mixture.
Denaturation at 94°C: In this process, the double stranded DNA molecule is denatured and opens into single stranded DNA.
Annealing at 54°C: After denaturation, the single stranded DNA attaches to the primer present in the tube.
Extension at 72 °C: At this temperature, the DNA polymerase enzyme works well and extends the chain further.