Polymerase chain reaction

What is the polymerase chain reaction (PCR)?

PCR is a method of making many copies of DNA.

Describe the process of PCR

Add DNA template to nucleotides, primer and Taq polymerase and add to thermocycler. Mixture is heated to 94-96°C to separate the two DNA strands. Mixture is cooled to 68°C to allow primers to bind to the template (annealing). Mixture is heated to 72°C to allow Taq polymerase to add nucleotides to the new strand (elongation). Process is repeated until required amount of DNA is obtained.

Explain how PCR is used in genetic fingerprinting

Traces of DNA from a crime scene can be amplified by PCR in order to identify criminals or samples can be used to show parent/child relationships.

What conditions make it difficult for PCR to be used?

• Two little DNA

• DNA damaged

• DNA in sample contaminated.