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DNA Fingerprinting and its use in crime detection.

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DNA FINGERPRINTING AND ITS USE IN CRIME DETECTION Several early civilizations were conscious of the distinctive nature of ridges and furrows on the tips of fingers. In 1858, William Herschel (an English civil servant) maintained that no two person's fingerprints are the identical, and they do not alter with age. Deoxyribonucleic acid (DNA) testing was initially used in the late 1970s to identify differences in blood levels in conjunction with blood diseases. In the mid-1980s the analysis advanced and was used to determine paternity. In 1984, a geneticist, Dr Jeffreys, created the set phrase "DNA fingerprints," and he explored the use of DNA testing in criminal investigations. He was able to create DNA profiles from body fluids, flesh skin and hair roots, by corresponding the genetic information from a forensic sample with a suspect. The widespread process of taking a suspect's fingerprints is called ink and roll. This is where a thin coating of black ink is rolled onto a metal plate, then one by one, each of the suspect's fingertips is rolled on the ink from one side of the nail to the other, and on to a white chart, producing prints. ...read more.


However, because there are so many millions of base pairs, the task would be time consuming. Instead, scientists are able to use a shorter method, because of repeating patterns in DNA. These patterns do not, however, give an individual "fingerprint," but they are able to determine whether two DNA samples are from the same person, related people or non-related people. Scientists use a small number of sequences of DNA that are known to vary among individuals and analyse those to get a certain probability match. Isolating the DNA in question from the rest of the cellular material in the nucleus is prepared. This can be prepared chemically, by using a detergent to wash the extra material from the DNA or repeatedly by applying a large amount of pressure to squeeze out the DNA. The pieces of DNA are then into a gel, such as agarose, and an electrical charge is applied to the gel, with negative charge at the top and the positive charge at the bottom. Because DNA has a slightly negative charge, the pieces of DNA will be attracted towards the bottom of the gel; the smaller pieces will be able to move more quickly towards the bottom than the larger pieces. ...read more.


DNA is not going to change from one individual to another and point to the incorrect individual. If a sample is deficient, there will be no result at all. Whilst a conviction based exclusively on DNA evidence is rare, DNA testing has proven to be influential in freeing convicted prisoners, who have been wrongly convicted. In Britain, for example, 16 points of likeness have got to be found to confirm a match. This amount varies in different countries. As the quantity of fingerprint records has grown, a computer system has been developed which is able to store the records and compare more than 60,000 fingerprints per second. Developments in DNA testing have pushed the boundaries of science and in addition have helped prove the guilt or innocence of alleged criminals. DNA fingerprinting is fast becoming the primary and most reliable method of identifying and distinguishing between individuals. The use of fingerprinting is also ideal for identifying runaways, rape victims or unidentified dead people. DNA does far more than certify our identity, and that of our ancestors, than it does to just catch criminals - even though the forensic arena is where the method is best utilized. ...read more.

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