It is widely known that each individual has a DNA profile as unique as a fingerprint. Actually, over 99% of all 3 billion nucleotides in human DNA which we inherit from each parent are identical among all individuals. However, for every 1000 nucleotides that we inherit there is 1 site of variation or polymorphism, in the population. These DNA polymorphisms change the length of the DNA fragments produced by the digestion of restriction enzymes . The resulting fragments are called restriction fragments length polymorphisms. Gel electrophoresis can be used to separate and determine the size of the RFLPs. The exact number and size of fragments produced by a specific restriction enzyme digestion varies from individual to individual.
DNA fingerprinting has proved valuable, not only for convicting felons and exonerating the innocent, but also for establishing maternity or paternity and proving family relationships. More exotic uses include the identification of missing children in Argentina, soldiers killed in war, and even the body of Nazi physician Joseph Mengele, the so-called “Angel of Death.”
The way it started:
The fundamental techniques involved in genetic fingerprinting were discovered serendipitously in 1984 by geneticist Alec J. Jeffreys of the University of Leicester in Great Britain while he was studying the gene for myoglobin, a protein that stores oxygen in muscle cells. He found that the myoglobin gene contains many segments that vary in size and composition from individual to individual and that have no apparent function. Jeffrey called these segments minisatellites because they were small and they surround the part of the gene that actually serves as a genetic bluprint. The minisatellites accountsfor less than 1 percent of the total DNA of a human. Jeffreys isolated several of these minisatellite genes and inserted each into bacteria, which produced large amounts of the DNA segments. These segments could.