Deoxyribonucleic acid. The substance that makes up the genetic blueprint of every living cell. Molecules that store information that affects the life of a man or woman: hair texture, height, colour of eyes or skin, etc all of which are determined in advance and recorded in the body’s DNA. Chemical decision-maker that decides all the characteristics of a child on coming into the world. DNA finger- printing is a unique method of identifying a person by DNA present in his body fluids or cells. A criminal may be convicted by leaving behind a tell-tale bit of skin, hair, etc.
Human nuclei have 46 chromosomes, each consisting of long, thin strands of DNA. The strands are so long because all required information contained in 3 to 4 million genes is stored in sequence in the DNA. In human bone it can survive for a millennium. A most important discovery has been the location of the gene for Huntington’s chorea on chromosome 4 made public in “Nature”, 18.3.93. Discoveries have also revealed genes relative to cystic fibrosis and sickle-cell anaemia.
The abbreviation for deoxyribonucleic acid, the principal molecule carrying genetic information in almost all organisms; the exceptions are certain viruses that use RNA. is found in the chromosomes of cells; its doublehelix structure allows the chromosomes to be copied exactly during the process of cell division. (See also nucleic acids.)
Deoxyribonucleic acid. A type of nucleic acid that preserves the information needed by the cell to tell it how to grow and it’s role in the scheme of things. Genes are made from DNA.
DNA is the abbreviation for deoxyribonucleic acid, one of the two types of NUCLEIC ACID that occur in nature. It is the fundamental genetic material of all CELLS, and is present in the nucleus of the cell where it forms part of the CHROMOSOMES and acts as the carrier of genetic information. The molecule is very large, with a molecular weight of several millions, and consists of two single chains of nucleotides (see NUCLEIC ACID) which are twisted round each other to form a double helix (or spiral). The genetic information carried by DNA is encoded along one of these strands. A gene, which represents the genetic information needed to form protein, is a stretch of DNA containing, on average, around 1,000 nucleotides paired in these two strands (see GENES).
To allow it to ful?l its vitally important function as the carrier of genetic information in living cells, DNA has the following properties. It is stable, so that successive generations of species maintain their individual characteristics, but not so stable that evolutionary changes cannot take place. It must be able to store a vast amount of information: for example, an animal cell contains genetic information for the synthesis of over a million proteins. It must be duplicated exactly before each cell division to ensure that both daughter cells contain an accurate copy of the genetic information of the parent cells (see GENETIC CODE).
Do Not Attempt Resuscitation order: an instruction, usually made by a patient while he or she has capacity and recorded in their notes, requesting that doctors desist from performing resuscitation in the event of physiological failure. By respecting a patient’s choice with regard to resuscitation, a doctor is respecting that patient’s *autonomy. If resuscitation is considered *futile, a decision not to attempt it may be taken; ideally, this should be communicated to the patient and the reasons explained sensitively.... dnar order
n. an enzyme that catalyses the cleavage of DNA. A genetically engineered form, recombinant human DNAse (dornase alfa), is used in the treatment of *cystic fibrosis to reduce the viscosity of the sticky secretions in the lungs. Administered by inhalation via a jet nebulizer, it appears to hydrolyse extracellular DNA that accumulates with other neutrophil debris in the airways. Trade name: Pulmozyme.... dnase
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