| 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) |
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| 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) |
| cloning, DNA | The use of DNA manipulation procedures to produce multiple copies of a single gene or segment of DNA. (12 Dec 1998) |
| molecules, recombinant DNA | A combination of DNA molecules of different origin that are joined using recombinant DNA technology. (12 Dec 1998) |
| competitor DNA | DNA from a test organism that is denatured and then used in in vitro hybridization experiments in which it competes with DNA (homologous) from a reference organism; used to determine the relationship of the test organism to the reference organism. (05 Mar 2000) |
| polymerase, DNA | Enzyme that catalyses (speeds) the polymerization of DNA. DNA polymerase uses preexisting nucleic acid templates and assembles the DNA from deoxyribonucleotides. (12 Dec 1998) |
| polymerase, DNA or RNA | Enzymes that catalyse the synthesis of nucleic acids on pre-existing nucleic acid templates, assembling RNA from ribonucleotides or DNA from deoxyribonucleotides. (05 Mar 2000) |
| covalently closed circular DNA | <molecular biology> A circular molecule of double-stranded DNA which is supercoiled, or coiled up on itself due to internal tensions, because there are no breaks in the phosphate backbone (upon which the nucleotide bases are mounted) to relieve the tensions and allow it to form an open circle. (09 Oct 1997) |