AskDefine | Define catabolism

Dictionary Definition

catabolism n : breakdown of more complex substances into simpler ones with release of energy [syn: katabolism, dissimilation, destructive metabolism] [ant: anabolism]

User Contributed Dictionary

English

Etymology

From καταβολή, from κατά + βάλλειν.

Noun

catabolism
  1. destructive metabolism, usually including the release of energy and breakdown of materials

Antonyms

Translations

Extensive Definition

For the related metabolic process, see anabolism.
Catabolism is the set of metabolic pathways which break down molecules into smaller units and release energy. 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.

References

catabolism in Arabic: تقويض
catabolism in Catalan: Catabolisme
catabolism in Danish: Katabolisme
catabolism in German: Katabolismus
catabolism in Estonian: Katabolism
catabolism in Spanish: Catabolismo
catabolism in Esperanto: Katabolo
catabolism in Persian: فروگشت
catabolism in French: Catabolisme
catabolism in Italian: Catabolismo
catabolism in Hebrew: קטבוליזם
catabolism in Norwegian: Katabolisme
catabolism in Occitan (post 1500): Catabolisme
catabolism in Polish: Katabolizm
catabolism in Portuguese: Catabolismo
catabolism in Russian: Катаболизм
catabolism in Simple English: Catabolism
catabolism in Slovenian: Katabolizem
catabolism in Swedish: Katabolism
catabolism in Turkish: Katabolizma
catabolism in Chinese: 异化作用

Synonyms, Antonyms and Related Words

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