| 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) |
| zwitter hypothesis | That an amphoteric molecule (e.g., an amino acid) has, at its isoelectric point, equal numbers of positive and negative charges, thus becoming a zwitterion. (05 Mar 2000) |
| frustration-aggression hypothesis | The theory that frustration may lead to aggression, but that aggression is always the result of some form of frustration. (05 Mar 2000) |
| Lyon hypothesis | <genetics> Hypothesis, first advanced by Lyon, concerning the random inactivation of one of the two X chromosomes of the cells of female mammals. In consequence females are chimaeric for the products of the X chromosomes, a situation that has been exploited in female Negroes (who are heterotypic for isozymes of glucose 6 phosphate dehydrogenase) as a means to confirm the monoclonal origin of papillomas and of atherosclerotic plaques. (20 Mar 1998) |