natural purification (자정 작용
| natural mutation | A mutation which occurs by itself without first being affected by a mutagen, for example during the process of DNA replication. Spontaneous mutations arise at a remarkably constant rate. The rate that spontaneous mutations arise has been used as an evolutionary clock to estimate how closely related two (or more) separate species are to each other. (09 Oct 1997) |
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| natural passive immunity | Immunity conferred by the mother on the foetus or newborn. (14 Nov 1997) |
| natural pigment | A naturally occurring coloured compound; absorbs light in the visible range of the electromagnetic spectrum. Compare: structural colour. Synonym: biochrome. (05 Mar 2000) |
| natural products | Naturally occurring compounds that are end products of secondary metabolism; often, they are unique compounds for particular organisms or classes of organisms. (05 Mar 2000) |
| natural selection | The hypothesis that genotype environment interactions occurring at the phenotypic level lead to differential reproductive success of individuals and hence to modification of the gene pool of a population. (18 Nov 1997) |
| immunity, natural | The capacity of a normal organism to remain unaffected by microorganisms and their toxins. It results from non-specific mechanisms such as genetic endowment, naturally occurring antiviral and bactericidal substances, phagocytosis, and constitutional factors such as body temperature, oxygen tension, and age. (12 Dec 1998) |
| killer cells, natural | Cells responsible for spontaneous cytotoxicity of a variety of tumour cells without prior immunization. These natural killer cells are found in non-immune humans and experimental animals and are thought by some to be the same as killer cells (killing by antibody-dependent cell cytotoxicity), but they can also kill in the absence of antibody. (12 Dec 1998) |
| affinity antibody | The measure of the interaction between molecules such as a receptor and its ligand. This interaction is reversible. (05 Mar 2000) |
| agglutinating antibody | 1. An antibody that causes clumping or agglutination of the bacteria or other cells which either stimulated the formation of the agglutinin, or contain immunologically similar, reactive antigen. Synonym: agglutinating antibody, immune agglutinin. 2. A substance, other than a specific agglutinating antibody, that causes organic particles to agglutinate, commonly qualified, e.g., plant agglutinin. (05 Mar 2000) |
| anaphylactic antibody | Antibody that has an affinity for certain kinds of cells, in addition to and unrelated to its specific affinity for the antigen that induced it, because of the properties of the Fc portion of the heavy chain. See: heterocytotropic antibody, homocytotropic antibody, cytotropic antibody test. Synonym: anaphylactic antibody, cytophilic antibody. (05 Mar 2000) |
| anti-basement membrane antibody | Autoantibodies to renal glomerular basement membrane antigens. (05 Mar 2000) |
| antibody | An immunoglobulin molecule that has a specific amino acid sequence by virtue of which it interacts only with the antigen that induced its synthesis in cells of the lymphoid series (especially plasma cells) or with antigen closely related to it. Antibodies are classified according to their ode of action as agglutinins, bacteriolysins, haemolysins, opsonins, precipitins, etc. (18 Nov 1997) |
| antibody affinity | A measure of the binding strength between antibody and a simple hapten or antigen determinant. It depends on the closeness of stereochemical fit between antibody combining sites and antigen determinants, on the size of the area of contact between them, and on the distribution of charged and hydrophobic groups. It includes the concept of "avidity," which refers to the strength of the antigen-antibody bond after formation of reversible complexes. (12 Dec 1998) |
| antibody aldolase | <enzyme> Prepared by reactive immuninization to catalyze a wide variety of aldol reactions and decarboxylations Registry number: EC 4.1.2.- Synonym: fab 33f12, aldolase catalytic antibody (26 Jun 1999) |
| antibody-coated bacteria test, urinary | Fluorescent antibody technique for visualizing antibody-bacteria complexes in urine. The presence or absence of antibody-coated bacteria in urine correlates with localization of urinary tract infection in the kidney or bladder, respectively. (12 Dec 1998) |