| centrifugalization | <procedure> The process of separating fractions of systems in a centrifuge. The most basic separation is to sediment a pellet at the bottom of the tube, leaving a supernatant at a given centrifugal force. In this case sedimentation is determined by size and density of the particles in the system amongst other factors. Density may be used as a basis for sedimentation in density gradient centrifugation. at very high g values molecules may be separated, i.e. Ultracentrifugation. In continuous centrifugation the supernatant is removed continuously as it is formed. (13 Nov 1997) |
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| centrifugation | <procedure> The process of separating fractions of systems in a centrifuge. The most basic separation is to sediment a pellet at the bottom of the tube, leaving a supernatant at a given centrifugal force. In this case sedimentation is determined by size and density of the particles in the system amongst other factors. Density may be used as a basis for sedimentation in density gradient centrifugation. at very high g values molecules may be separated, i.e. Ultracentrifugation. In continuous centrifugation the supernatant is removed continuously as it is formed. (13 Nov 1997) |
| centrifugation, density gradient | Separation of particles according to density by employing a gradient of varying densities. at equilibrium each particle settles in the gradient at a point equal to its density. (12 Dec 1998) |
| centrifugation, isopycnic | Centrifugation in which the solvent is of the same density as the substance to be isolated. From the greek iso-, equal and pyknos, thick. (12 Dec 1998) |
| centrifugation, zonal | Centrifugation using a rotating chamber of large capacity in which to separate cell organelles by density-gradient centrifugation. (12 Dec 1998) |
| centrifuge | A laboratory apparatus that separates mixed samples into homogenouscomponent layers by spinning them at high speed. (09 Oct 1997) |
| centrilobular | at or near the centre of a lobule, e.g., of the liver. (05 Mar 2000) |
| centrilobular emphysema | Emphysema affecting the lobules around their central bronchioles, causally related to bronchiolitis, and seen in coal-miner's pneumoconiosis. Synonym: centri-acinar emphysema. (05 Mar 2000) |
| centrin | <plant biology> Acidic phosphoproteins (20 kD), homologous to caltractin, found in striated flagella roots of various flagellated algae, centromsomal region of some mammalian cells and basal bodies of human sperm. (25 Jun 1999) |
| centriolar region | See: pericentriolar region or centrosome. (18 Nov 1997) |
| centriole | <cell biology> They are self-replicating, short, fibrous, rod-shaped organelles of animal cells. Each centriole is a short cylinder containing nine pairs of peripheral microtubules, arranged orthogonally so as to form the wall of the cylinder. Almost identical to basal body of cilium. The pericentriolar material, but not the centriole itself, is the major microtubule organising centre of the cell. Centrioles divide prior to mitosis and the daughter centrioles and their associated pericentriolar material come to lie at the poles of the spindle. (25 Jun 1999) |
| centripetal | Synonym: afferent. 2. Denoting the direction of the force pulling an object toward an axis of rotation. Synonym: axipetal. Origin: L. Centrum, centre, + peto, to seek (05 Mar 2000) |
| centripetal current | The direction of current flow in a nerve when the anode is placed peripheral to the cathode, in contrast to descending current; the convention used is that current flows from positive to negative. Synonym: centripetal current. (05 Mar 2000) |
| centripetal nerve | <anatomy, physiology> A nerve which transmits impulses from the tissues to the brain and spinal cord (for example sensory nerve). (27 Sep 1997) |
| centro- | Combining form denoting centre. Origin: G. Kentron (05 Mar 2000) |