| estrous cycle | The series of physiologic uterine, ovarian, and other changes that occur in higher animals, consisting of proestrus, estrus, postestrus, and anestrus or diestrus. (05 Mar 2000) |
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| estrus cycle | A reproductive cycle in some female mammals (but not female humans, who instead have menstrual cycles). The cycle is characterised by a short period of intense sexual desire (called estrus or heat) when the animal is fertile, which often occurs only once or twice a year, and involves correlating physical changes of the reproductive tract. (09 Oct 1997) |
| exoerythrocytic cycle | That nonpathogenic portion of the vertebrate phase of the life cycle of malarial organisms that takes place in liver cells, outside of the blood cells. (05 Mar 2000) |
| exogenous cycle | The portion of a parasitic life cycle occurring outside the host. (05 Mar 2000) |
| fatty acid oxidation cycle | A series of reactions involving acyl-coenzyme A compounds, whereby these undergo beta oxidation and thioclastic cleavage, with the formation of acetyl-coenzyme A; the major pathway of fatty acid catabolism in living tissue. (05 Mar 2000) |
| urea cycle | The metabolic pathway isfound in vertebrates and takes place in theliver, in it, urea is synthesised from amino acids and carbon dioxide. (09 Oct 1997) |
| Krebs cycle | <biochemistry> Tricarboxylic acid cycle or citric acid cycle. (18 Nov 1997) |
| Krebs-Henseleit cycle | The metabolic pathway isfound in vertebrates and takes place in theliver, in it, urea is synthesised from amino acids and carbon dioxide. (09 Oct 1997) |
| Krebs-Kornberg cycle | A catabolic cycle in plants and microorganisms like that of the tricarboxylic acid cycle in animals; its key reaction is the condensation of acetyl-CoA with glyoxylic acid to malic acid (analogous to the condensation of acetyl-CoA and oxaloacetic acid to form citric acid in the tricarboxylic acid cycle). Synonym: Krebs-Kornberg cycle. (05 Mar 2000) |
| forced cycle | <cardiology, physiology> A cardiac cycle (atrial or ventricular) that is cut short by a forced beat. (05 Mar 2000) |
| fuel cycle | The series of steps required to produce electricity. The fuel cycle includes mining or otherwise acquiring the raw fuel source, processing and cleaning the fuel, transport, electricity generation, waste management and plant decommissioning. (05 Dec 1998) |
| futile cycle | <biochemistry> Any seqence of enzyme catalysed reactions in which the forward and reverse processes (catalysed by different enzymes) are consititutively active. Frequently used to describe the cycle of phosphorylation and dephosphorylation of phosphatidyl inositol derivatives in cell membranes. (05 Jan 1998) |
| lytic cycle | The general life cycle of a lytic virus, from infection of the host cell, hijacking of the host cells mechanisms, use of the host cells mechanisms to produce viral components, and assembly of the components into progeny viruses, to the destruction of the host cell by rupturing its plasma membrane (lysis) and the release of the progeny viruses so that they can spread and infect other cells. (09 Oct 1997) |