DNA Fingerprinting and its use in crime detection.

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Michelle Greenfield         PAGE 1        01/05/2003

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.  Fingerprint records are kept so that a suspect’s fingerprints discovered at a scene can be checked against any existing records.  An investigation is then executed by specialists, who look for points of similarity between the prints.  In the late 19th century, Edward Henry (British Police Officer), developed a method of categorizing fingerprints.  He stated that all fingerprints could be organized in to four key categories: arches, loops, whorls and composites (including all three patterns).

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DNA is a chemical structure that forms chromosomes.  A piece of a chromosome that dictates a particular trait is called a gene.  Structurally, DNA is a double helix: two strands of genetic material spiralled around each other.  Each strand contains a sequence of bases, also called nucleotides.  A base is one of four chemicals, adenine, guanine, cytosine and thymine.  The two strands of DNA are connected at each base and each base will only bond with one other base.  Adenine (A) will only bond with thymine (T) and guanine (G) WILL ONLY BOND WITH CYTOSINE (C).  If a one ...

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