| catabolic pathway | <biochemistry> A series of reactions in a metabolic pathway that break down complex compounds into simpler ones, usually releasing energy in the process. Compare: anabolic pathway. (16 Mar 1998) |
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| pathway | 1. A collection of axons establishing a conduction route for nerve impulses from one group of nerve cells to another group or to an effector organ composed of muscle or gland cells. 2. Any sequence of chemical reactions leading from one compound to another; if taking place in living tissue, usually referred to as a biochemical pathway. (05 Mar 2000) |
| visual pathway | Neural paths and connections within the central nervous system, beginning with the retina and terminating in the occipital cortex. (05 Mar 2000) |
| pentose phosphate 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) |
| perforant pathway | A pathway of fibres originating in the lateral part of the entorhinal area, perforating the subiculum of the hippocampus, and running into the stratum moleculare of the hippocampus, where these fibres synapse with others that go to the dentate gyrus. It is also called the perforating fasciculus. (12 Dec 1998) |
| mercapturic acid pathway | A glutathione-dependent pathway for the detoxification of a number of compounds, including arene oxides; an S-substituted glutathione is formed and ultimately converted to a mercapturic acid (an S-substituted N-acetylated l-cysteine), which is excreted; the leukotrienes are believed to be degraded through this pathway. (05 Mar 2000) |
| RMP pathway | <biochemistry> Ribulose monophosphate pathway, also called allulose phosphate pathway. A metabolic pathway used by methylotropic bacteria for the conversion of formaldehyde to hexose sugars etc. In the first stage ribulose 5 phosphate is condensed with HCHO. (23 Aug 1998) |
| phosphogluconate pathway | <biochemistry> This oxidative pathway starts with glucose-6-phosphate andeventually results in the creation of pentose phosphates and NADPH. (09 Oct 1997) |
| polyol 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) |
| critical pathway | Schedules of medical and nursing procedures, including diagnostic tests, medications, and consultations designed to effect an efficient, coordinated program of treatment. (12 Dec 1998) |
| Hatch Slack Kortshak 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) |
| 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) |
| 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) |