Energy metabolism definitions

Introduction to metabolism Definition of catabolic and anabolic pathways INTRODUCTION TO METABOLISM (p. 89) Most pathways can be classified as either catabolic (they degrade complex molecules to a few simple products, such as C02, NH3, and water) or anabolic (they synthesize complex end-products from simple precursors). Catabolic reactions also capture chemical energy in the form of ATP from the degradation of energy-rich molecules. Anabolic reactions require energy, which is generally provided by the breakdown of ATP. 

Hofman T, Lees H (1953) The biochemistry of nitrifying organisms 4. The respiration and intermediary metabolism of Nitrosomonas. Biochem J 54 579-583 Holliger C, Wohlfarth G, Diekert G (1999) Reductive dehalogenation in the energy metabolism of anaerobic bacteria. FEMS Microbiol Rev 22 383-398 Hollocher TC, Tate ME, Nicholas DJD (1981) Oxidation of ammonia by Nitrosomonas europaea definitive lsO-tracer evidence that hydroxylamine formation involves a monooxygenase. J Biol Chem 256 10834-10836... 

The fact that a Lewis acid is able to accept an electron pair means that it must have either a vacant, low-energy orbital or a polar bond to hydrogen so that it can donate H+ (which has an empty7 Is orbital). Thus, the Lewis definition of acidity includes many species in addition to H+. For example, various metal cations, such as Mg2+, are Lewis acids because they accept a pair of electrons when they form a bond to a base. We ll also see in later chapters that certain metabolic reactions begin with an acid-base reaction between Mg2+ as a Lewis acid and an organic diphosphate or triphosphate ion as the Lewis base. 

Active transport. The definition of active transport has been a subject of discussion for a number of years. Here, active transport is defined as a membrane transport process with a source of energy other than the electrochemical potential gradient of the transported substance. This source of energy can be either a metabolic reaction (primary active transport) or an electrochemical potential gradient of a substance different from that which is actively transported (secondary active transport). 

There is not only a controversy over nomenclature but there is also a comparable discussion over the number of metabolites in the metabolome. Almost by definition, any substance involved in metabolism either as a product of metabolism or necessary for metabolism should be considered, and estimates of 3000 major metabolites have been reported.9 Others have indicated that any metabolite smaller than 1000 Da, which would incorporate virtually all energy pathways, all catabolic pathways, and many biosynthetic pathways, might be reasonable.5... 

Muravskaya, 1978 Diana and Mackay, 1979 Shatunovsky, 1980). However, in all starved fish it is the lipid that is mobilized first, except possibly in the eel. In fatty fish, much lipid is used from the flesh, while in lean fish it is used from the liver. In both types of fish, muscle protein is mobilized only when the lipid resources fall below a critical level. Black and Love (1986) showed that energy substrates are mobilized in a definite sequence, white muscle protein, for example, being metabolized at an earlier stage than red muscle protein, while, on refeeding, the latter is replenished before the former. 

Give the definition and function of an energy carrier species in metabolism. 

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