Pub. date: 2002 | Online Pub. Date: September 15, 2007 | DOI: 10.4135/9781412950664 | Print ISBN: 9780761922582 | Online ISBN: 9781412950664| Publisher:SAGE Publications, Inc.About this encyclopedia
William C. Thompson
English geneticist Alec Jeffreys first described a method for “typing” human DNA in 1985. Since that time, DNA typing technology has advanced rapidly, and the new DNA tests have been embraced eagerly by the criminal justice system. DNA tests are now routinely used to help identify the source of blood, semen, hair, and other biological materials found at crime scenes and to establish family relationships in cases of disputed parentage. DNA tests have helped prosecutors obtain convictions in thousands of cases, and they have helped establish the innocence of thousands of individuals who might otherwise have become suspects. Deoxyribonucleic acid, or DNA, is a long, double-stranded molecule configured like a twisted ladder or “double helix.” The genetic information of all organisms is encoded in the sequence of four organic compounds (bases) that make up the rungs of the DNA ladder. Most DNA is tightly packed into structures called chromosomes in ...