| DNA polymorphism | A condition in which one of two different but normal nucleotide sequences can exist at a particular site in DNA. (05 Mar 2000) |
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| DNA primase | <enzyme> A single-stranded DNA-dependent RNA polymerase that functions to initiate, or prime, DNA synthesis by synthesizing a nucleotide RNA polymer. Registry number: EC 2.7.7.- (12 Dec 1998) |
| DNA primers | Short sequences (generally about 10 base pairs) of DNA that are complementary to sequences of messenger RNA and allow reverse transcriptases to start copying the adjacent sequences of mRNA. Primers are used extensively in genetic and molecular biology techniques. (12 Dec 1998) |
| DNA probe | <molecular biology> A small piece of nucleic acid that has been labelled with a radioactive isotope, dye, or enzyme and is used to locate a complementary nucleotide sequence or gene on a DNA molecule. (14 Nov 1997) |
| DNA probes | Species- or subspecies-specific DNA (including complementary DNA (DNA, complementary), conserved genes, whole chromosomes, or whole genomes) used in hybridization studies in order to identify microorganisms, to measure DNA-DNA homologies, to group subspecies, etc. The DNA probe hybridises with a specific mRNA, if present. Conventional techniques used for testing for the hybridization product include dot blot assays, southern blot assays, and DNA:RNA hybrid-specific antibody tests. Conventional labels for the DNA probe include the radioisotope labels 32p and 125i and the chemical label biotin. The use of DNA probes provides a specific, sensitive, rapid, and inexpensive replacement for cell culture techniques for diagnosing infections. (12 Dec 1998) |
| DNA probes, HLA | DNA probes specific for the human leukocyte antigen genes, which represent the major histocompatibility determinants in humans. The four known loci are designated as a, b, c, and d. Specific antigens are identified by a locus notation and number, e.g., HLA-a11. The inheritance of certain HLA alleles is associated with increased risk for certain diseases (e.g., insulin-dependent diabetes mellitus). (12 Dec 1998) |
| DNA probes, HPV | DNA probes specific for the identification of human papilloma virus. (12 Dec 1998) |
| DNA profiling | <molecular biology> See restriction fragment length polymorphism. (18 Nov 1997) |
| DNA-protein interaction | <molecular biology> Any complex that forms between a protein molecule and DNA. Examples are nucleosomes (structures formed for the purpose of DNA storage) and any gene regulatory protein (a protein which regulates transcription by binding to a regulatory region on the DNA). (09 Oct 1997) |
| DNA, protozoan | Deoxyribonucleic acid that makes up the genetic material of protozoa. (12 Dec 1998) |
| DNA puff | <molecular biology> An area on a chromosome where transcription of DNA into mRNA, or replication of DNA is occurring, resulting in an enlarged, puffy appearance of the area. Similar to chromosome puff, except generalised to any type of chromosome in any type of organism. (09 Oct 1997) |
| DNA rearrangement | <molecular biology> Wholesale movement of sequences from one position to another in DNA, such as occur somatically, for example in the generation of antibody diversity. (18 Nov 1997) |
| DNA, recombinant | Biologically active DNA which has been formed by the in vitro joining of segments of DNA from different sources. It includes the recombination joint or edge of a heteroduplex region where two recombining DNA molecules are connected. (12 Dec 1998) |
| DNA renaturation | <molecular biology> The reformation of double stranded DNA from thermally denatured DNA. The rate of reassociation depends upon the degree of repetition and is slowest for unique sequences (this is the basis of the Cot value). (18 Nov 1997) |
| DNA repair | <molecular biology> Each cell has a series of special enzymes to correct the errors in DNA structure and sequence. This protects genetic information against environmental damage and replication errors and restore the DNA to its original state. (25 Jun 1999) |