| DNA entry nuclease | <chemical> Mw 75kda; from membranes of competent bacillus subtilis cells; shows DNA-binding and nuclease activity; believed to be involved in entry of DNA into competent b subtilis cells (26 Jun 1999) |
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| DNA excision | <molecular biology> The removal of a damaged segment of a DNA molecule by a group of DNA repair enzymes in order to repair the molecule. (09 Oct 1997) |
| DNA filter assay | <molecular biology> A lab technique used to identify the complementary base sequences of DNA. It involves immobilising the DNA on a filter and putting it in a solution that contains radioactively-labelled probe DNA or RNA molecules. (09 Oct 1997) |
| DNA fingerprint | <molecular biology> The unique pattern of DNA fragments identified by Southern hybridisation (using a probe that binds to a polymorphic region of DNA) or by polymerase chain reaction (using primers flanking the polymorphic region). (09 Oct 1997) |
| DNA fingerprinting | <molecular biology> See restriction fragment length polymorphism. (18 Nov 1997) |
| DNA footprinting | <molecular biology> Technique for identifying the recognition site of DNA binding proteins: See: footprinting. (18 Nov 1997) |
| DNA fragmentation | Endonucleolytic cleavage of genomic DNA into oligonucleosomal fragments at internucleosomal sites. DNA fragmentation along with chromatin condensation are considered the hallmarks of apoptosis. (12 Dec 1998) |
| DNA gap | A localised loss of one of the two strands in the double helix of DNA. (05 Mar 2000) |
| DNA gene | <molecular biology> Any of a number of genes found in the bacteria Escherichia coli which makes proteins that are essential for DNA replication. (09 Oct 1997) |
| DNA glycosylase | <enzyme, molecular biology> Class of enzymes involved in DNA repair. They recognise altered bases in DNA and catalyse their removal by cleaving the glycosidic bond between the base and the deoxyribose sugar. at least 20 such enzymes occur in cells. (18 Nov 1997) |
| DNA gyrase | <enzyme, molecular biology> A type II topoisomerase of Escherichia coli, that is essential for DNA replication. This enzyme can induce or relax supercoiling. (18 Nov 1997) |
| DNA helicase | <enzyme, molecular biology> A prokaryote enzyme that uses the hydrolysis of ATP to unwind the DNA helix at the replication fork, to allow the resulting single strands to be copied. Two molecules of ATP are required for each nucleotide pair of the duplex. (18 Nov 1997) |
| DNA helicases | <enzyme> Proteins that promote unwinding of duplex DNA during replication by binding cooperatively to single-stranded regions of DNA or to short regions of duplex DNA that are undergoing transient opening. Registry number: EC 5.99.- (12 Dec 1998) |
| DNA helix | The helical structure assumed by two strands of deoxyribonucleic acid, held together throughout their length by hydrogen bonds between bases on opposite strands, referred to as Watson-Crick base pairing. See: base pair. Synonym: DNA helix, double helix, twin helix. (05 Mar 2000) |
| DNA homology | <molecular biology> How closely related two or more separate strands of DNA are to each other, based on their base sequences. (09 Oct 1997) |
| genomic DNA | <molecular biology> The DNA which is found in the organisms genome and is passed on to offspring as information necessary for survival. The phrase is used to distinguish between other types of DNA, such as found within plasmids. (09 Oct 1997) |
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| recombinant DNA | <molecular biology> Spliced DNA formed from two or more different sources that have been cleaved by restriction enzymes and joined by ligases. (18 Nov 1997) |
| recombinant DNA molecules | A combination of DNA molecules of different origin that are joined using recombinant DNA technology. (12 Dec 1998) |
| recombinant DNA technologies | Procedures used to join together DNA segments in a cell-free system (an environment outside a cell ororganism). Under appropriate conditions, a recombinant DNA molecule canenter a cell and replicate there, either autonomously or after it hasbecome integrated into a cellular chromosome. (09 Oct 1997) |
| recombinant DNA technology | 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) |
| relaxed DNA | <molecular biology> DNA that isn't supercoiled. (09 Oct 1997) |
| repetitive DNA | <molecular biology> Nucleotide sequences in DNA that are present in the genome as numerous copies. Originally identified by the C0t_ value derived from kinetic studies of DNA renaturation. These sequences are not thought to code for polypeptides. One class of repetitive DNA, termed highly repetitive DNA, is found as short sequences, 5-100 nucleotides, repeated thousands of times in a single long stretch. It typically comprises 3-10% of the genomic DNA and is predominantly satellite DNA. Another class, which comprises 25-40% of the DNA and termed moderately repetitive DNA, usually consists of sequences about 150 to 300 nucleotides in length dispersed evenly throughout the genome and includes Alu sequences and transposons. (18 Nov 1997) |
| replication, DNA | A wondrous complex process whereby the ( parent ) strands of DNA in the double helix are separated and each one is copied to produce a new ( daughter ) strand. This process is said to be semi-conservative since one of each parent strand is conserrved and remains intact after replication has taken place. (12 Dec 1998) |
| melting temperature of DNA | That temperature at which, under a given set of conditions, double-stranded DNA is changed (50%) to single-stranded DNA; under standard conditions, the base composition of the DNA can be estimated from the denaturation temperature, since the greater the denaturation temperature, the greater the guanine-plus-cytosine content (i.e., GC content) of the DNA. Synonym: melting temperature of DNA. (05 Mar 2000) |
| chimeric DNA | <molecular biology> A molecule of DNA that has resulted from recombination, or has resulted from DNA from two sources being spliced together. (05 Jan 1998) |
| chloroplast DNA | <molecular biology> A circular molecule of DNA found in all photosynthetic plants which codes for the function of photosynthesis. (09 Oct 1997) |
| RNA-directed DNA polymerase | <enzyme> An enzyme that synthesises DNA on an RNA template. It is encoded by the pol gene of retroviruses and by certain retrovirus-like elements. Chemical name: Deoxynucleotide-triphosphate:DNA deoxynucleotidyltransferase (RNA-directed) Registry number: EC 2.7.7.49 (12 Dec 1998) |
| Pfu DNA polymerase | <enzyme> From pyrococcus furiosus; shows sequence homology with alpha-like DNA polymerases; amino acid sequence given in first source Registry number: EC 2.7.7.- Synonym: pfu polymerase (26 Jun 1999) |
| circular DNA | <molecular biology> C.f. Linear DNA. Examples: plasmids, bacterial, mitochondrial, chloroplast and some viral genomes. (18 Nov 1997) |
| MIP1 DNA polymerase | <enzyme> From saccharomyces cerevisiae; has structural similarity with the E coli DNA polymerase i-type enzymes Registry number: EC 2.7.7.- Synonym: mip1 gene product (26 Jun 1999) |