| site-specific mutagenesis | <cell culture, molecular biology> An in vitro technique in which an alteration is made at a specific site in a DNA molecule, which is then reintroduced into a cell. Various techniques are used, for the cell biologist, a very powerful approach to determining which parts of a protein or nucleotide sequence are critical to function. (18 Nov 1997) |
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| site specific mutation | An alteration of the structure of a gene at a specific sequence, usually referring to experimentally produced changes in gene sequence. (05 Mar 2000) |
| site-specific recombination | <molecular biology> A type of recombination that occurs between two specific short DNA sequences present in the same or in different molecules. An example is the integration and excision of _ prophage. (18 Nov 1997) |
| soluble specific substance | A soluble type-specific polysaccharide produced during active growth of virulent pneumococci composing a large part of the capsule. Synonym: pneumococcal polysaccharide, soluble specific substance, specific soluble polysaccharide, specific soluble sugar. (05 Mar 2000) |
| species-specific | Applying only to a particular species, said of effects that vary depending on the species in question. (09 Oct 1997) |
| species-specific antigen | Antigenic components in the tissues and fluids of members of a species of animal, by means of which various species may be immunologically distinguished; e.g., serum albumin of horses is immunologically different from that of man, dogs, sheep, and so on. (05 Mar 2000) |
| specific | 1. Pertaining to a species. 2. Produces by a single kind of microorganism. 3. A remedy specially indicated for any particular disease. 4. <immunology> Pertaining to the special affinity of antigen for the corresponding antibody. Origin: L. Specificus (18 Nov 1997) |
| specific absorbance | Absorbance per unit of concentration. See: specific absorption coefficient. (05 Mar 2000) |
| specific absorption coefficient | Absorbance (of light) per unit path length (usually the centimeter) and per unit of mass concentration. Compare: molar absorption coefficient. Synonym: absorbancy index, absorptivity, extinction coefficient, specific extinction. (05 Mar 2000) |
| specific action | The action of a drug or a method of treatment which has a direct and especially curative effect upon a disease, e.g., the action of vitamin B12 in pernicious anaemia. (05 Mar 2000) |
| specific active immunity | See: acquired immunity. (05 Mar 2000) |
| specific activity | 1. <chemistry> The number of activity units (whatever is appropriate) per unit of mass, volume or molarity. 2. <radiobiology> Total activity of a given nuclide per gram of a compound, element or radioactive nuclide. Perhaps most often usage, in the context of radiochemicals, the number of microcuries per micromole. (16 Dec 1997) |
| specific anergy | A reduction of the normal or usual immunologic response resulting from a reaction to a specific allergen. Synonym: specific anergy. (05 Mar 2000) |
| specific antigens | Antigen's that characterise a single genus of microorganisms. (05 Mar 2000) |
| specific antiserum | See: antiserum. (05 Mar 2000) |