| equilibrium centrifugation | A type of density gradient centrifugation used to separate proteins or nucleic acids from a mixture. (09 Oct 1997) |
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| equilibrium constant | <chemistry> The ratio of the reverse and forward rate constants for a reaction of the type: A + B = AB at equilibrium the equilibrium constant (K) equals the product of the concentrations of reactants divided by the concentration of product and has dimensions of concentration. Kd = (concentration A.concentration B) / (concentration AB). The affinity constant (Ka) is the reciprocal of the equilibrium constant. Dimension: moles per litre. In general the concept of Kd is more readily understood than that of Ka, for example: in considering the conversion of A to AB by the binding of ligand B, the Kd = B when A = AB. Thus Kd is equal to the ligand concentration which produces half maximal conversion (response). (10 Jan 1998) |
| equilibrium dialysis | In immunology, a method for determination of association constants for hapten-antibody reactions in a system in which the hapten (dialyzable) and antibody (nondialyzable) solutions are separated by semipermeable membranes. Since at equilibrium the quantity of free hapten will be the same in the two compartments, quantitative determinations can be made of hapten-bound antibody, free antibody, and free hapten. (05 Mar 2000) |
| equilibrium potential | <physiology> The membrane potential at which a particular type of ion or other particle does not diffuse through the membrane in either direction. (09 Oct 1997) |
| linkage equilibrium | <genetics> Situation that should exist in a population undisturbed by selection, migration, etc., in which all possible combinations of linked genes should be present at equal frequency. The situation is no more common than are such undisturbed populations. (18 Nov 1997) |
| banding | <dentistry> The process of cementing orthodontic bands to your teeth. (08 Jan 1998) |
| banding of chromosomes | Treatment of chromosomes to reveal characteristic patterns of horizontal bands. Thanks to these banding patterns that resemble bar codes, each human chromosome is distinctive and can be identified without ambiguity. (12 Dec 1998) |
| banding pattern | <genetics> Chromosomes stained with certain dyes, commonly quinacrine (Q banding) or Giemsa (G banding), show a pattern of transverse bands of light and heavy staining that is characteristic for the individual chromosome. The basis of the differential staining, which is the same in most tissues, is not understood: each band represents 5-10% of the length, about 10exp7 base pairs, although this is not true for polytene chromosomes in Drosophila that show more than 4000 bands. (18 Nov 1997) |
| BrDu-banding | The labeling of chromosomes in proliferating tissue by adding an excess of bromodeoxyuridine, which replaces the uridine incorporated in RNA and fluoresces in ultraviolet light; the bands result from sister chromatid exchanges. (05 Mar 2000) |
| G-banding | <genetics> Chromosomes stained with certain dyes, commonly quinacrine (Q banding) or Giemsa (G banding), show a pattern of transverse bands of light and heavy staining that is characteristic for the individual chromosome. The basis of the differential staining, which is the same in most tissues, is not understood: each band represents 5-10% of the length, about 10exp7 base pairs, although this is not true for polytene chromosomes in Drosophila that show more than 4000 bands. (18 Nov 1997) |
| G-banding stain | <technique> A unique chromosome staining technique, used in human cytogenetics to identify individual chromosomes, which produces characteristic bands. It utilises acetic acid fixation, air drying, denaturing chromosomes mildly with proteolytic enzymes, salts, heat, detergents, or urea, and finally Giemsa stain; chromosome bands appear similar to those fluorochromed by Q-banding stain. Synonym: Giemsa chromosome banding stain. (05 Mar 2000) |
| R-banding | See: R-banding stain. (05 Mar 2000) |
| R-banding stain | <technique> A reverse Giemsa chromosome banding method that produces bands complementary to G-bands; induced by treatment with high temperature, low pH, or acridine orange staining; often used together with G-banding on human karyotype to determine whether there are deletions. (05 Mar 2000) |
| Giemsa chromosome banding stain | <technique> A unique chromosome staining technique, used in human cytogenetics to identify individual chromosomes, which produces characteristic bands. It utilises acetic acid fixation, air drying, denaturing chromosomes mildly with proteolytic enzymes, salts, heat, detergents, or urea, and finally Giemsa stain; chromosome bands appear similar to those fluorochromed by Q-banding stain. Synonym: Giemsa chromosome banding stain. (05 Mar 2000) |
| C banding | <molecular biology> Method of defining chromosome structure by staining with Giemsa and looking at the banding pattern in the heterochromatin of the centromeric regions. Giemsa banding (G banding) of the whole chromosome gives higher resolution. Q banding is done with quinacrine. (18 Nov 1997) |