Restriction Fragment Length Polymorphism (RFLP)
The DNA isolated from an individual organism has a unique sequence and even the members within a species differ in some parts of their sequence. The restriction sites would also vary and hence if DNA from a given individual was subjected to digestion with a restriction enzyme the fragments generated would vary when compared with another individual's DNA similarily digested. This variation in size (length) of the restriction enzyme generated fragments among individuals within a given species is termed RFLP. A schematic representation of how RFLPs are generated is given below (Fig. 3). A major application of this technique is DNA fingerprinting analysis which is explained below.
Fig. 3. RFLP technique.
Individuals except identical twins vary in their RFLP pattern as indicated schematically in the agarose gel electrophoresis. Hence the term DNA fingerprint is used and this is the basis of a major technique used in forensic science to identify and relate individuals.