Anabolism

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With anabolism or building metabolism (from ancient Greek αναβολισμός anabolismós , German 'throwing up' ) one describes the structure of substances in living beings . The opposite of anabolism is catabolism , the breakdown of substances. Catabolism and anabolism are part of metabolism .

Definitions

The more precise definitions contained in the literature are similar but different.

The definition of the totality of the anabolic metabolic reactions is widespread . Strictly speaking, this also includes some exergonic material conversions for the purpose of energy generation , insofar as more complex ones arise from simpler substances, such as the reduction of carbon dioxide CO 2 with hydrogen H 2 to acetic acid CH 3 COOH (a form of homoacetate fermentation ) and the oxidation of hydrogen H 2 with oxygen O 2 to water H 2 O ( oxyhydrogen reaction ) in some bacteria . In general technical usage, however, such conversions of substances which serve to generate energy are not referred to as anabolism.

In part, this definition is restricted to the structure of the body's own substances , which excludes all substance conversions in which the products are excreted, such as the formation of antibiotics and the aforementioned oxyhydrogen reaction. In a further variation, only the “linking of simple molecules to more complex molecules” is referred to as anabolism and thus the involvement of atoms and monoatomic ions is excluded. Since atoms and monatomic ions cannot be products of a structure and atoms are not known as starting materials for structural reactions, this definition only excludes monatomic ions as starting materials, but this exclusion is not justified.

Further definitions denote the totality of the endergonic (energy-consuming) metabolism as anabolism. This also includes the formation of substances that are excreted. Variations of this definition are restricted to the endergonic structure of substances or to the endergonic structure of molecules . It can be assumed that endergonic metabolism, which is only a partial reaction of a reaction sequence that is exergonic as a whole and serves to generate energy (catabolism), should be excluded, for example the formation of sugar - phosphoric acid ester to initiate glycolysis .

Energy demand

Most of the time, energy is required to build up substances . In chemotrophic organisms , it is obtained from chemical, energy-releasing ( exergonic ) material conversions, in phototrophic organisms from light . The energy from the sources mentioned is first converted into a short-term energy store and carrier, namely adenosine triphosphate (ATP). ATP serves as a direct energy source in the energy-consuming building reactions. If a reducing agent is also required to build up the body's own substances , NADPH is used for this purpose , which is formed in phototrophs by the light reaction and in chemotrophs by the oxidation of substances.

Structure of molecules

The simplest molecules made by the anabolic process of photosynthesis are simple sugars . These sugar molecules are converted by further anabolic processes; among other things, amino acids , isoprenoids and nucleotides are formed . Complex molecules such as proteins , fats , carbohydrates , genetic material or lignin can then be formed from these precursors .

See also

literature

Web links

Wiktionary: anabolism  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ↑ Lexicon of Biology . Herder, Freiburg et al., 1983, p. 166.
  2. ^ Brockhaus ABC Biology . Brockhaus, Leipzig 1986, p. 861.
  3. ^ Meyers Taschenlexikon Biologie . 2nd Edition. BI-Taschenbuchverlag, Mannheim, Vienna, Zurich 1988.
  4. ^ Gertrud Scherf: Dictionary of Biology . DTV, Munich 1997, p. 25.
  5. ↑ Lexicon of Biology . Spektrum, Heidelberg 1999, p. 310.
  6. ↑ Compact Lexicon of Biology . Spectrum, Heidelberg 2001.
  7. ↑ Peter H. Raven, George B. Johnson, Jonathan B. Losos, Susan R. Singer: Biology . 7th edition. McGraw-Hill, Boston et al. O. 2005, Glossary S. G-1.
  8. ↑ Eike Libbert: General Biology . UTB 1197, 7th edition. Gustav Fischer, Jena 1991, pp. 33, 149.
  9. ↑ Daniel N. Lapedes (ed.): McGraw-Hill Dictionary of the life sciences . McGraw-Hill, New York et al. 1976, pp. 45-46.
  10. ^ William K. Purves, David Sadava, Gordon H. Orians, H. Craig Heller: Biologie . 7th edition. Translation into German, Spektrum Elsevier, Munich 2006 (Original: 2004), p. 128.
  11. ↑ Peter H. Raven, George B. Johnson, Jonathan B. Losos, Susan R. Singer: Biology . 7th edition. McGraw-Hill, Boston et al. O. 2005, p. 155 (here the definition mentioned first is also used elsewhere).
  12. ^ A b Neil A. Campbell, Jane B. Reece: Biology . 8th edition. Translation into German, Pearson Studies, Munich 2009.
  13. ↑ G. Czihak, H. Langer, H. Ziegler (eds.): Biology - A textbook . 6th edition. Springer, Berlin et al., 1996, p. 87.