Restriction Fragment Length Polymorphism (RFLP)

RFLP is a technique that is not widely used now but it was one of the first techniques used for DNA analysis in forensic science. Large sample sizes are needed for RFLP relative to newer techniques - usually a sample would need to be approximately the size of a one-pound coin. While that in itself may sound small, it is large relative to other techniques such as PCR analysis that require only a few cells for successful sequencing. In RFLP, the different lengths of DNA fragments are analysed. These fragments are from the digestion of a sample of DNA with a restriction endonuclease enzyme. The enzyme chops DNA in a certain style - the restriction endonuclease recognition site. Whether or not particular recognition sites are present will provide different lengths of DNA fragments, which are then divided up through electrophoresis. DNA probes then serve to hybridise the fragments through complementary binding.