| cis configuration | <molecular biology> The configuration of an organic molecule containing a double bond between two carbon atoms, where the largest, most complex R groups are on the same side: H H \ / C=C / \ H3C CH3 -OR-The configuration of an organic molecule containing a ring, where the largest, most complex R groups are on the same side: H H | ___ \ / | // \\ [ring viewed edge-on] | \___/ / \ | /---\ H3C CH3 | H3C CH3. A genetics term meaning an event or a gene whose action occurs on the same chromosome. Two mutations in different genes coding for the same phenotype which are on the same chromosome (as opposed to the trans configuration where each homologue has one of the mutations). Compare: trans configuration. (11 Jan 1998) |
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| cis dominance | <molecular biology> When a gene or promoter affects only gene activity in the DNA duplex molecule in which it is placed the effect is referred to as cis, as opposed to trans effects when a gene or promoter on one DNA molecule can affect genes on another DNA molecule. Cis dominance is seen only when the appropriate pair or set of genes are all cis to each other. (18 Nov 1997) |
| cis-isoprenyltransferase | <enzyme> Cis-isoprene units of dolichyl monophosphate are added to trans,trans-farnesyl pyrophosphate using isopentenyl pyrophosphate as donor; from embryonic rat brain Registry number: EC 2.5.1.- Synonym: long-chain cis-isoprenyltransferase (26 Jun 1999) |
| cis-prenyl transferase | <enzyme> Involved in dolichol biosynthesis Registry number: EC 2.5.1.- Synonym: cis-prenyltransferase (26 Jun 1999) |
| cis-toluene dihydrodiol dehydrogenase | <enzyme> Nad specific dehydrogenase; reduces ring structure Chemical name: 1,2-dihydroxy-3-methylcyclohexa-3,5-diene dehydrogenase Registry number: EC 1.3.- Synonym: ctd dehydrogenase (26 Jun 1999) |
| 11-cis-retinal | The isomer of retinaldehyde that can combine with opsin to form rhodopsin; it is formed from 11-trans-retinal by retinal isomerase. Synonym: neoretinal b. (05 Mar 2000) |
| 11-cis-retinol | Retinol with cis configuration at the 11-position (carotenoid numbering) or 5'-position (retinol numbering) of the side chain; an intermediate in the vision cycle. Synonym: neoretinene B. (05 Mar 2000) |
| 9-cis-retinol dehydrogenase | <enzyme> Catalyses oxidation of 9-cis-retinol to 9-cis-retinaldehyde; does not catalyze oxidation of all-trans-retinol; genbank u89717 Registry number: EC 1.1.1.- Synonym: retinol dehydrogenase (9-cis) (26 Jun 1999) |
| Abbe test plate | <equipment> A long, wedge-shaped coverslip about 0.20 mm thick at one end and 0.10 to 0.12 mm at the other end coated chemically with a silver film on which are ruled horizontal lines. at each variation in thickness of 0.01 mm there are vertical lines. By means of oblique illumination and by focusing on different portions of the plate, it is possible to determine the optimum coverslip thickness for any objective and also, for microscopes with drawtubes, the tube length for best objective performance. The approximate freedom from spherical and chromatic aberrations can also be estimated. Small isolated bits of silver near the edges of the lines form good objects for the star test (05 Aug 1998) |
| acetone test | A test for ketonuria; the suspected urine is shaken up with a few drops of sodium nitroprusside, and strong ammonia water is then gently poured over the mixture; if acetone is present, a magenta ring forms at the line of contact; tablets containing sodium nitroprusside and alkali are now more commonly used. (05 Mar 2000) |
| achievement test | A standardised test used to measure acquired learning, e.g., competence in a specific subject area such as reading or arithmetic, in contrast to an intelligence test which is a useful index of potential ability or learning. (05 Mar 2000) |
| acidified serum test | Lysis of the patient's red cells in acidified fresh serum, specific for paroxysmal nocturnal haemoglobinuria. Synonym: Ham's test. (05 Mar 2000) |
| acid loading test | <nephrology> This is a test used in the diagnosis of renal tubular acidosis. The patient takes ammonium chloride capsules for 3 days to acidify the blood (lower blood pH). A sample of the urine and the blood is then collected and the results are interpreted. (27 Sep 1997) |
| acid perfusion test | <gastroenterology, investigation> A test used to diagnosis gastrooesophageal reflux disease. This investigation requires that the patient swallow 3 tiny tubes into the stomach. A mixture of hydrochloric acid (like stomach acid) and saline are alternatively injected into the tubes. The patient then reports any symptoms they may have. Some patients may vomit. (13 Nov 1997) |
| acid phosphatase test for semen | A screening test for semen by determining acid phosphatase content; because seminal fluid contains high concentrations of acid phosphatase, while other body fluids and extraneous foreign materials have very low concentrations, high values of acid phosphatase on vaginal aspirate or lavage, or on wash fluid from stains, render positive identification of semen, even if the male is aspermic. (05 Mar 2000) |