| AC | abdominal circumference; abdominal compression; absorption coefficient; abuse case; acetate; acetylc... |
|---|---|
| ACI | acceleration index; acoustic comfort index; acute cardiac ischemia; acute coronary infarction; acute... |
| ACSA | adenylate cyclase-stimulating activity |
| ACSP | adenylate cyclase-stimulating protein |
| AdC | adenylate cyclase; adrenal cortex |
| chemiosmotic hypothesis | <biochemistry, cell biology> A theoretical mechanism (proposed by Mitchell) to explain energy transduction in the mitochondrion. As a general mechanism it is the coupling of one enzyme catalysed reaction to another using the transmembrane flow of an intermediate species. For example Cytochrome oxidase pumps protons across the mitochondrial inner membrane and ATP synthesis is driven by re entry of protons through the ATP synthesising protein complex. The alternative model is production of a chemical intermediate species, but no compound capable of coupling these reactions has ever been identified. (18 Nov 1997) |
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| Michaelis-Menten hypothesis | <chemistry> That a complex is formed between an enzyme and its substrate (the O'Sullivan-Tompson hypothesis), which complex then decomposes to yield free enzyme and the reaction products (Brown hypothesis), the latter rate determining the overall rate of substrate-product conversion. See: Michaelis-Menten constant, Michaelis-Menten equation. (05 Mar 2000) |
| mnaemic hypothesis | The theory that stimuli or irritants leave definite traces (engrams) on the protoplasm of the animal or plant, and when these stimuli are regularly repeated they induce a habit which persists after the stimuli cease; assuming that the germ cells share with the nerve cells in the possession of engrams, acquired habits may thus be transmitted to the descendants. Synonym: mnaemic theory, mnemism, Semon-Hering theory. (05 Mar 2000) |
| wobble hypothesis | <molecular biology> Explains why the base Inosine is included in position 1 in the anticodons of various t RNAs, why many mRNA codon words translate to a single amino acid, why there are appreciably fewer t RNAs than mRNA codon types and why the redundant nature of the genetic code translates into a precise set of 20 amino acids. Inosine in Position 1 in the anticodon can base pair with A, u or C in position 3 in the mRNA codon, so that for example UCU, UCC, UCA all code for Serine using an inosine anticodon. (18 Nov 1997) |
| sequence hypothesis | Francis Crick's seminal concept that genetic information exists as alinear DNA code, DNA and protein sequence are colinear. (09 Oct 1997) |
| hypothesis | <statistics> A supposition that appears to explain a group of phenomena and is advanced as a basis for further investigation, a proposition that is subject to proof or to an experimental or statistical test. (11 Jan 1998) |
| sliding filament hypothesis | The theory that the contracting muscle shortens because two sets of filaments slide past each other. (05 Mar 2000) |
| Starling's hypothesis | The principle that net filtration through capillary membranes is proportional to the transmembrane hydrostatic pressure difference minus the transmembrane oncotic pressure difference; although well established, it is called Starling's hypothesis to distinguish it from Starling's law of the heart. (05 Mar 2000) |
| Neyman-Pearson statistical hypothesis | A formal conjecture about the numerical value of a parameter to be tested exclusively in the light of an immediate set of data without attention to prior knowledge or convictions and ignoring other sets of evidence treated in a similar fashion. The answer is a statement not about whether the hypothesis is true but whether it is an acceptable explanation of the data or should be rejected in favour of another hypothesis. (05 Mar 2000) |
| null hypothesis | The assumption that any observed difference between two samples of a statistical population is purely accidental and not due to systematic causes. (05 Dec 1998) |
| dual recognition hypothesis | An outmoded hypothesis that is known to be incorrect now that the structure of the T-cell receptor is known. The proposal was that viral (and some chemical) antigens were recognised in association with histocompatibility antigens by separate receptors on the T-cell. The generation of cytotoxic T-cells was by association with Class I MHC antigens, of T helper cells by association with Class II MHC antigens. See: altered self hypothesis. (18 Nov 1997) |
| insular hypothesis | An obsolete theory of the origin of diabetes mellitus from destruction or loss of function of the islets of Langerhans in the pancreas. (05 Mar 2000) |
| endosymbiont hypothesis | The hypothesis that semi autonomous organelles such as mitochondria and chloroplasts were originally endosymbiotic bacteria or cyanobacteria. The arguments are convincing and although the hypothesis cannot be proven it is widely accepted. (18 Nov 1997) |
| uniform rate hypothesis | <biology> This states that any two evolving organismal lineages diverge from a common ancestor at a constant rate with respect to each other. (09 Oct 1997) |
| unineme hypothesis | <cell biology, molecular biology> This states that that a chromatid has only one DNA duplex, which goes from one end of the chromatid to the other. (09 Oct 1997) |