DNA preparations of ten individuals of a population of hypothetical yum-yum trees, the products electrophoressed and a southern blot or S-blot was probed by hybridisation with a with a cloned fragment of the trees genome.

For this particular combination of the restriction enzyme and hybridization probe, the pattern of hybridizing bands was obtained. The length of the restriction fragments recognized by the probe is dimophic (has two forms) in this population. Other probe restriction enzyme combination may identify more than two differently sized fragments. The phenomenon is known as Restriction Fragment Length Polymorphism.

Uses of RFLP:

• They are molecular markers used in creating maps of chromosomes.
• In forensics, they are used to test whether a tissue sample left at a scene (blood, skin, sperm etc.) could have come from the suspect.
• In plant and animal breeding, they can which backcross progeny most resemble the desired parent. Therefore RFLP's are used where biological parentage is an issue.