| two-carbon fragment | The acetyl group (CH3CO-) that takes part in transacetylation reactions with coenzyme A as carrier; commonly referred to as acetate or acetic acid, from which it is derived. (05 Mar 2000) |
|---|---|
| anovulatory cycle | A sexual cycle in which no ovum is discharged. (05 Mar 2000) |
| Born-Haber cycle | <physics> This is a mathematical description of the relationship between the electron affinity, heats of atomisation, ionisation energy and lattice energy of ionic compounds. (09 Oct 1997) |
| bottoming cycle | A cogeneration system in which steam is used first for process heat and then for electric power production. (05 Dec 1998) |
| brain wave cycle | The complete upward and downward excursion of a single wave, complex, or impulse as seen on an electroencephalogram. (05 Mar 2000) |
| c3 cycle | <biochemistry> The part of the photosynthesis process where carbon dioxide is converted into three-carbon compounds, which can then be turned into six-carbon sugars. (07 Nov 1997) |
| c4 cycle | <plant biology> An alternative, very efficient pathway used by plants living in areas with low levels of carbon dioxide, to convert carbon dioxide into a form usable by the plants during photosynthesis. (09 Oct 1997) |
| Calvin Benson cycle | <biochemistry, plant biology> Metabolic pathway responsible for photosynthetic carbon dioxide fixation in plants and bacteria. The enzyme that fixes carbon dioxide is RuDP carboxylase. The cycle is the only photosynthetic pathway in C3 plants and the secondary pathway in C4 plants. The enzymes of the pathway are present in the stroma of the chloroplast. (18 Nov 1997) |
| calvin cycle | In plants, a cyclical series of carbon-fixing, sugar-producing reactions in the chloroplasts. Some of the sugars (triose phosphates) are recycled, others are stored as carbohydrates. Light is not needed for these reactions, they use the carbon dioxide and energy produced in the light reactions of photosynthesis. (09 Oct 1997) |
| cardiac cycle | The complete round of cardiac systole and diastole with the intervals between, or commencing with, any event in the heart's action to the moment when that same event is repeated. (05 Mar 2000) |
| gamma-glutamyl cycle | A proposed pathway for the glutathione-dependent transport of certain amino acids (most notably l-cystine, l-methionine, and l-glutamine) and dipeptides into certain cells; this cycle requires the formation of gamma-glutamyl amino acids and gamma-glutamyl dipeptides as well as a protein for the translocation of these di-and triisopeptides into the cells. (05 Mar 2000) |
| genesial cycle | The reproductive period of a woman's life. (05 Mar 2000) |
| visual cycle | The transformation of carotenoids involved in the bleaching and regeneration of the visual pigment. (05 Mar 2000) |
| cell cycle | <cell biology, molecular biology> The sequence of events between mitotic divisions. The cycle is conventionally divided into G0, G1, (G standing for gap), S (synthesis phase during which the DNA is replicated), G2 and M (mitosis). Cells that will not divide again are considered to be in G0 and the transition from G0 to G1 is thought to commit the cell to completing the cycle and dividing. (26 Mar 1998) |
| cell cycle proteins | Proteins that control the cell division cycle. This family of proteins includes a wide variety of classes, including cyclin-dependent kinases, mitogen-activated kinases, cyclins, and phosphoprotein phosphatases (phosphoprotein phosphatase) as well as their putative substrates such as chromatin-associated proteins, cytoskeletal proteins, and transcription factors. (12 Dec 1998) |