DNA fingerprinting is also called DNA typing. Alec Jeffreys is credited with developing this technique in 1984. Jeffreys found that within each gene, certain sequences of DNA are not required to do anything. In a sense, they simply exist within the gene. Normally, these sequences are named minisatellites. The minisatellites are unique to individuals. The only individuals which have been found to share satellites are those born from the same zygote (identical multiples in birth, cannot be fraternal). DNA fingerprinting has been used in paternity and crimes.
In order to complete a DNA fingerprint, cells mast be collected. Typical collection cells are hair, skin, and blood. After being purified, cut, electrified, split, and exposed to radioactive pieces of other DNA, the patterns of minisatellites emerge.
DNA, which stands for deoxyribonucleic acid, is genetic material present in the nucleus of every cell and is what determines individual characteristics such as eye color, hair color, and height. DNA fingerprinting, also called genetic fingerprinting or restriction mapping, is a method of characterizing an individual's DNA. Formulated by British geneticist Alec Jeffreys, the existence of a DNA fingerprint is based on the assumption that every person (except identical twins) has a unique sequence of DNA.
DNA fingerprinting has many uses, among them, determining an individual's identity, confirming familial relationships, and establishing the range of genetic differences within a population. In criminal investigations, hair, blood, and skin samples left by a criminal can yield a DNA fingerprint, which may be matched to a suspect's DNA fingerprint.
Within the DNA molecule, which resembles an endless twisting ladder, the sequence of the genetic information is repeated many times. The length of the sequence, the number of repetitions, and precise location of the sequence within the DNA chain are unique in every person. The odds against two individuals who are not identical twins having the same DNA fingerprint are 30 billion to one.
A process has been developed that translates the sequences of genetic information into a visual record that resembles a bar code. In this process, the technician isolates the DNA from blood, saliva, hair follicles, or semen. The next step is to place the DNA into an enzyme solution, which separates the DNA strand into thousands of shorter pieces. Finally, the fragments, placed in a gelatin-like material, are subjected to a strong electrical current that separates them according to size and electrical behavior.
Sources: Hazen, Robert M., and James Trefil. Science Matters: Achieving Scientific Literacy, pp. 241-42; How in the World?: A Fascinating Journey Through the World of Human Ingenuity, pp. 94-95; nell, James E. Latest Intelligence, p. 54.