| DNA sequencing | <molecular biology> Any lab technique used to find out the sequence of nucleotide bases in a DNA molecule or fragment. Examples are dideoxy sequencing and Maxam-Gilbert sequencing. (09 Oct 1997) |
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| DNA shearing | <molecular biology> The tearing apart of unusually long DNA molecules by mechanical rather than chemical means, sometimes by accident when the molecule is being prepared in the lab for testing. (09 Oct 1997) |
| DNA, single-stranded | A single chain of deoxyribonucleotides that occurs in some bacteria and viruses. It usually exists as a covalently closed circle. (12 Dec 1998) |
| DNA supercoiling | <molecular biology> The condition of DNA coiling up onitself because its helix has been bent, overwound or underwound. (09 Oct 1997) |
| DNA, superhelical | Circular duplex DNA isolated from viruses, bacteria and mitochondria in supercoiled or supertwisted form. This superhelical DNA is endowed with free energy. During transcription, the magnitude of RNA initiation is proportional to the DNA superhelicity. (12 Dec 1998) |
| DNA synaptase | <enzyme> Fuses double stranded DNA molecules at a region of homology Registry number: EC 6.- (26 Jun 1999) |
| DNA synthesis | <molecular biology> The linking together of nucleotides (as deoxyribonucleotide triphosphates) to form DNA. In vivo, most synthesis is DNA replication, but incorporation of precursors also occurs in repair. In the special case of retroviruses, DNA synthesis is directed by an RNA template (see reverse transcriptase). (18 Nov 1997) |
| DNA synthesiser | <molecular biology> A machine which automatically makes short, artificial polynucleotides or oligonucleotides with any desired sequence of nucleotide bases. (09 Oct 1997) |
| DNA technology, recombinant | A series of procedures used to join together (recombine) DNA segments. A recombinant DNA molecule is constructed (recombined) from segments from 2 or more different DNA molecules. Under certain conditions, a recombinant DNA molecule can enter a cell and replicate there, autonomously (on its own) or after it has become integrated into a chromosome. (12 Dec 1998) |
| DNA topoisomerase | <enzyme, molecular biology> An enzyme capable of altering the degree of supercoiling of double stranded DNA molecules. Various topoisomerases can increase or relax supercoiling, convert single stranded rings to intertwined double stranded rings, tie and untie knots in single stranded and duplex rings, catenate and decatenate duplex rings. Topoisomerase II of E. Coli = gyrase. (18 Nov 1997) |
| DNA topoisomerase (ATP-hydrolysing) | <enzyme> An ATP-requiring enzyme which, in the presence of magnesium ions, introduces negative supertwists into closed and possibly linear duplex DNA. The enzyme is implicated in DNA replication and transcription. It causes the storage of mechanical strain energy in the superhelical turns of DNA at the expense of ATP hydrolysis. Chemical name: DNA topoisomerase (ATP-hydrolysing) Registry number: EC 5.99.1.3 (12 Dec 1998) |
| DNA transfection | <molecular biology> A technique originally developed to allow viral infection of animal cells by uptake of purified viral DNA rather than by intact virus particles. Term is now generally used to describe applications of same methodology to introduction of other kinds of genes or gene fragments into cells as DNA, such as activated oncogenes from tumours into tissue culture cells. (18 Nov 1997) |
| DNA tumour virus | <oncology, virology> Virus with DNA genome that can cause tumours in animals. Examples are Papovaviridae, Adenoviridae and Epstein Barr virus. (18 Nov 1997) |
| DNA tumour viruses | DNA viruses producing malignant tumours. Of the six major groupings of DNA viruses four contain members which are actually or potentially oncogenic: the adenoviridae, the herpesviridae, the papovaviridae, and the poxviridae. (12 Dec 1998) |
| DNA twisting | <molecular biology> The coiling of a double-stranded DNA molecule in the opposite direction than the direction that the helix turns. (09 Oct 1997) |