Genetic techniques: polymerase Chain Reaction (PCR)

• Used to amplify number of copies of a specific region of DNA.
• Region to amplified is specified by the choice of primers (Short chain DNA with sequence matches the ends of the region of interest.) used.

Cyclic process, Procedure:
1. In the first cycle, double stranded DNA templates are denatured by heating to a temperature of 95oC to single strands
2. Reaction mixture is cooled and allow primers to bind to the single-stranded DNA; providing an active site for DNA polymerase (thermostable polymerase: allows the cycling to continue with minimal loss of enzymatic activity.) which synthesis the complementary strand.
3. Subsequent cycle, primers blind to both the original DNA and the newly synthesised DNA: resulting in an exponential increase in the number of copies which are visualized using agarose gel electrophoresis and spectometrically.

Types of PCR:

1. Nested PCR
2. RT-PCR
3. Real-time PCR

References: K. Sanderson and D. Nichols, University of Tasmania, Australia. 2003. Genetic techniques: PCR, NASBA, Hybridisation and microarrays. In: Thomas A. McMeekin. Detecting pathogens in food. North America: CRC Press LLC.259-260.