| salvage pathway | <biochemistry> A recycling metabolic pathway in which biomolecules such as nucleotides are synthesised from intermediates in the degradative pathway for those biomolecules. The intermediate materials would otherwise be waste products. (14 Oct 1997) |
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| hexose monophosphate pathway | <biochemistry> A pathway of hexose oxidation in which glucose-6-phosphate undergoes two successive oxidations by NADP, the final one being an oxidative decarboxylation to form a pentose phosphate. Diverges from this when glucose-6-phosphate is oxidized to ribose 5 phosphate by the enzyme glucose-6 phosphate dehydrogenase. This step reduces NADP to NADPH, generating a source of reducing power in cells for use in reductive biosyntheses. In plants, part of the pathway functions in the formation of hexoses from carbon dioxide in photosynthesis. Also important as source of pentoses, for example for nucleic acid biosynthesis. This pathway is the main metabolic pathway in neutrophils, congenital deficiency in the pathway produces sensitivity to infection. Alternative metabolic route to Embden Meyerhof pathway for breakdown of glucose. (18 Nov 1997) |
| hexose monphosphate pathway | A metabolic pathway present in a wide range of prokaryotic and eukaryotic microorganisms as well as in plants and animals, it involves the oxidative decarboxylation of glucose-6-phosphate, via 6 phosphogluconate, to ribulose 5-phosphate, followed by a series of reversible, non-oxidative interconversions whereby hexose and triose phosphates are formed from pentose phosphates. (09 Oct 1997) |
| HSK pathway | <biochemistry> Metabolic pathway responsible for primary carbon dioxide fixation in C4 plant photosynthesis. The enzymes that are found in mesophyll chloroplasts include PEP carboxylase, that adds carbon dioxide to phosphoenolpyruvate to give the 4 carbon compound, oxaloacetate. Four carbon compounds are transferred to bundle sheath chloroplasts, where the carbon dioxide is liberated and re fixed by the Calvin Benson cycle. The Hatch Slack Kortshak pathway permits efficient photosynthesis under conditions of high light intensity and low carbon dioxide concentration, avoiding the nonproductive effects of photorespiration. Acronym: HSK pathway (15 Nov 1997) |
| sorbitol pathway | A pathway responsible for d-fructose formation from sorbitol; increases in activity as the glucose concentration rises in diabetes. Synonym: polyol pathway. (05 Mar 2000) |
| neural pathway | <anatomy> Neural tracts connecting one part of the nervous system with another. (12 Dec 1998) |
| de novo pathway | <biochemistry> A pathway for synthesising a biomolecule from simple precursor molecules. Compare: salvage pathway. (12 Jan 1998) |
| DNA repair pathway | The sequence of steps in the repair of DNA. Each step is governed by an enzyme. (12 Dec 1998) |
| drug development pathway | The various procedures and studies that must be undertaken to satisfy Food and Drug Administration requirements for drug approval and marketing. (14 Nov 1997) |
| intrinsic pathway | <haematology> Initiation of blood clotting as a result of factors released from damaged tissue, as opposed to contact with a foreign surface (the intrinsic pathway). Tissue thromboplastin (Factor III) in conjunction with Factor VII proconvertin) will activate Factor X that, once activated, converts prothrombin to thrombin. (27 Jun 1999) |
| Embden-Meyerhof-Parnas pathway | A pathway that degrades glucose to pyruvate, the six-carbon stage converts glucose to fructose-1,6-bisphosphate, and the three-carbon stage produces ATP while changing glyceraldehyde-3-phosphate to pyruvate. Compare: Entner-Doudoroff pathway. (09 Oct 1997) |
| Embden-Meyerhof pathway | The main pathway for anerobic degradation of carbohydrate. Starch or glycogen is hydrolysed to glucose 1 phosphate and then through a series of intermediates, yielding two ATP molecules per glucose and producing either pyruvate which feeds into the tricarboxylic acid cycle) or lactate. (18 Nov 1997) |
| Entner-Douderoff pathway | A degradative pathway for carbohydrates in certain microorganisms (e.g., Pseudomonas sp.) that lack hexokinase, phosphofructokinase, and glyceraldehyde-3-phosphate dehydrogenase. (05 Mar 2000) |
| Entner-Doudoroff pathway | <biochemistry> A pathway that converts glucose to pyruvate and glyceraldehyde-3 phosphate by producing 6-phosphogluconate and then dehydrating it. (09 Oct 1997) |
| extrinsic pathway | <haematology> Initiation of blood clotting as a result of factors released from damaged tissue, as opposed to contact with a foreign surface (the intrinsic pathway). Tissue thromboplastin (Factor III) in conjunction with Factor VII proconvertin) will activate Factor X that, once activated, converts prothrombin to thrombin. (27 Jun 1999) |