Catabolism

Catabolism

:"For the related metabolic process, see anabolism."

Catabolism is the set of metabolic pathways which break down molecules into smaller units and release energy. [cite web |url=http://www.chem.qmul.ac.uk/iupac/bioinorg/CD.html#8 |title=Glossary of Terms Used in Bioinorganic Chemistry: Catabolism |accessdate=2007-10-30 |last=de Bolster |first=M.W.G. |date=1997 |publisher=International Union of Pure and Applied Chemistry] In catabolism, large molecules such as polysaccharides, lipids, nucleic acids and proteins are broken down into smaller units such as monosaccharides, fatty acids, nucleotides and amino acids, respectively. As molecules such as polysaccharides, proteins and nucleic acids are made from long chains of these small monomer units, the large molecules are called polymers.

Cells use the monomers released from breaking down polymers to either construct new polymer molecules, or degrade the monomers further to simple waste products, releasing energy. Cellular wastes include lactic acid, acetic acid, carbon dioxide, ammonia, and urea. The creation of these wastes is usually an oxidation process involving a release of chemical free energy, some of which is lost as heat, but the rest is used to drive the synthesis of adenosine triphosphate (ATP). This molecule acts as a way for the cell to transfer the energy released by catabolism to the energy-requiring reactions which make up anabolism. Catabolism therefore provides the chemical energy necessary for the maintenance and growth of cells. Examples of catabolic processes include glycolysis, the citric acid cycle, the breakdown of muscle protein in order to use amino acids as substrates for gluconeogenesis and breakdown of fat in adipose tissue to fatty acids.

There are many signals which control catabolism. Most of the known signals are hormones and the molecules involved in metabolism itself. Endocrinologists have traditionally classified many of the hormones as anabolic or catabolic, depending on which part of metabolism they stimulate. The "classic" catabolic hormones known since the early 20th century are cortisol, glucagon, and adrenaline (and other catecholamines). In recent decades, many more hormones with at least some catabolic effects have been discovered, including cytokines, orexin and hypocretin (a hormone pair), and melatonin.

See also

* Metabolism
* Anabolism
* Hydrolysis
* Dehydration synthesis

References


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Look at other dictionaries:

  • catabolism — CATABOLÍSM s.n. Proces biologic de transformare a unor substanţe complexe, specifice organismului, în alte substanţe mai simple şi nespecifice, pe care organismul le elimină; dezasimilaţie, dezasimilare. – Din fr. catabolisme. Trimis de valeriu,… …   Dicționar Român

  • catabolism — n. the breakdown of more complex substances into simpler ones with release of energy, in living organisms; destructive or downward metabolism; a form of metabolism, opposed to {anabolism}. See also {Disassimilation}. [Formerly spelled… …   The Collaborative International Dictionary of English

  • catabolism — catabolism. См. диссимиляция. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • catabolism — (n.) 1876, katabolism, destructive metabolism, from Gk. katabole a throwing down (also a foundation ), from kataballein to throw down, from kata down (see CATA (Cf. cata )) + ballein to throw (see BALLISTICS (Cf …   Etymology dictionary

  • catabolism — ► NOUN ▪ the breakdown of complex molecules in living organisms to form simpler ones, together with the release of energy. The opposite of ANABOLISM(Cf. ↑anabolism). DERIVATIVES catabolic adjective. ORIGIN from Greek katabol throwing down …   English terms dictionary

  • catabolism — [kə tab′ə liz΄əm] n. [< CATA + Gr bolē, a throw < ballein, to throw (see BALL2) + ISM] the process in a plant or animal by which living tissue is changed into energy and waste products of a simpler chemical composition; destructive… …   English World dictionary

  • catabolism — Metabolism Me*tab o*lism, n. (Physiol.) 1. The act or process, by which living tissues or cells take up and convert into their own proper substance the nutritive material brought to them by the blood, or by which they transform their cell… …   The Collaborative International Dictionary of English

  • catabolism — Disassimilation Dis as*sim i*la tion, n. (Physics) The decomposition of complex substances, within the organism, into simpler ones suitable only for excretion, with evolution of energy, a normal nutritional process the reverse of assimilation;… …   The Collaborative International Dictionary of English

  • catabolism — katabolizmas statusas T sritis chemija apibrėžtis Metabolizmo fazė. atitikmenys: angl. catabolism; dissimilation rus. диссимиляция; катаболизм ryšiai: sinonimas – disimiliacija …   Chemijos terminų aiškinamasis žodynas

  • catabolism — noun Etymology: Greek katabolē throwing down, from kataballein to throw down, from kata + ballein to throw more at devil Date: 1876 degradative metabolism involving the release of energy and resulting in the breakdown of complex materials (as… …   New Collegiate Dictionary

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