DNA

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DNA

n. scientifically, deoxyribonucleic acid, a chromonal double chain (the famous "double helix") in the nucleus of each living cell the combination of which determines each individual's hereditary characteristics. In law, the importance is the discovery that each person's DNA is different and is found in each living cell, so a hair, blood, skin or any part of the body can be used to identify and distinguish an individual from all other people. DNA testing can result in proof of one's involvement or lack of involvement in a crime scene. While recent DNA tests have proved a convicted killer on death row did not commit a crime and resulted in his release, current debate concerns whether DNA evidence is scientifically certain enough to be admitted in trials. The trend is strongly in favor of admission.

DNA

abbreviation for deoxyribonucleic acid, a chemical which is found in virtually every cell in the body and which carries genetic information. Except for identical twins, each person's DNA is unique. DNA profiling doesn't allow the examination of every single difference between people's DNA so the concentration will be on those aspects which are most likely to yield a difference. DNA can be extracted from any cells that contain a structure called the nucleus, for example, blood, semen, saliva or hair.

Mitochondrial DNA is inherited only from a person's mother. Brothers and sisters have the same mitochondrial DNA type as their mother. This feature of mitochondrial DNA can be used for body identification. The γ-chromosome is present only in men and is largely unchanged as it passes through the male line of a family. The usefulness of the technique in criminal matters is vastly enhanced by the extent to which it is possible to compare a sample with other individuals. To this end there is a National DNA Database maintained by the ASSOCIATION OF CHIEF POLICE OFFICERS and managed by the FORENSIC SCIENCE SERVICE. Techniques vary. There is a UK offence of DNA theft. It is also of assistance in paternity matters.

References in periodicals archive ?
Researchers trying to document the existence and role of cell-surface DNA bear a heavier burden of proof than scientists who happen upon more plausible discoveries.
But he had enough faith in his data to predict that securely bound surface DNA would be rediscovered.
Bennett and his co-workers at Oregon Health Sciences university in Portland stumbled across surface DNA while looking for a cell-membrane receptor for the iron-transporting protein lactoferrin.
While trypsin had failed to block the binding of lactoferrin, they discovered that it did prevent DNA from binding to the cell membrance, suggesting the presence of a membrane protein that binds to DNA.
Bennett and his colleagues further demonstrated that the DNA binds to the receptor in the same way hormones bind to their cell-surface receptors.
Bennett's team found additional evidence for the receptor's DNA specificity upon discovering that the cell would stop sequestering DNA when they exposed it to a chemical that inhibits protein synthesis.
Several biologists, upon learning of Bennett's work from SCIENCE NEWS, have expressed doubt that the DNA-binding protein represents a specific receptor for DNA. More likely, they say, it's a protein with a different purpose that also happens to bind to DNA.
Forte have isolated a particular stretch of DNA that they suspect contains the gene coding for the protein, and are now trying to clone the gene for the DNA receptor, Forte told SCIENCE NEWS.
So far, Bennett reports, he and his colleagues have found the DNA receptor on human liver, kidney and white blood cells (macrophages and T- and B-lymphocytes) and on kidney, liver and spleen cells from mice.
Although Bennett's and Emlen's results suggesting that surface DNA appears on many cell types seem inconsistent with earlier findings, Bennett says this may be because DNA's surface interactions are dynamic rather than static, as the earlier researchers had assumed.
After finding the proposed DNA receptor, Bennett began to wonder if cell-surface DNA might play some role in systemic lupus erythematosus, rheumatoid arthritis, Sjogren's syndrome and other autoimmune disorders involving connective tissues.