Outline the use of polymerase chain reaction (PCR) to copy and amplify minute quantities of DNA.

PCR is a way of producing large quantities of a specific target sequence of DNA.

It is useful when only a small amount of DNA is available for testing  (e.g. crime scene samples of blood, semen, tissue, hair, etc.).

 

PCR occurs in a thermal cycler and involves a repeat procedure of 3 steps:

1.  Denaturation:  DNA sample is heated to separate it into two strands

2.  Annealing:  DNA primers attach to opposite ends of the target sequence

3.  Elongation:  A heat-tolerant DNA polymerase (Taq) copies the strands 

 

- One cycle of PCR yields two identical copies of the DNA sequence