Metabolism

Santorio Santorio (1561-1636) in his steelyard balance, from Ars de statica medecina, first published 1614 Metabolism (from μεταβολισμος ("metabolismos"), the Greek word for "change", or "overthrow" (Etymonline)), is the biochemical modification of chemical compounds in living organisms and cells. This includes the biosynthesis of complex organic molecules (anabolism) and their breakdown (catabolism). Metabolism usually consists of sequences of enzymatic steps, also called metabolic pathways. The total metabolism are all biochemical processes of an organism. The cell metabolism includes all chemical processes in a cell. Without metabolism we would not be able to survive. Contents 1 Metabolic pathways 1.1 General pathways 1.2 Catabolism 1.3 Anabolism 1.4 Drug metabolism 1.5 Nitrogen metabolism 1.6 Other 2 History 3 See also 4 External links Metabolic pathways Important metabolic pathways are: General pathways Carbohydrate metabolism Fatty acid metabolism Citric acid cycle (Krebs cycle, tricarboxylic acid cycle) Catabolism Catabolic pathways that breakdown complex molecules into simple compounds: Cellular respiration, metabolic pathways that create energy (ATP and NADPH) from fuel molecules. These pathways are also involved in the digestion of food. Carbohydrate catabolism Glycogenolysis, the conversion of glycogen into glucose. Glycolysis, the conversion of glucose into pyruvate and ATP, does not require oxygen. Embden-Meyerhof pathway, the common glycolysis pathway. Entner-Doudoroff Pathway, an alternative glycolysis pathway in few bacteria. Pentose phosphate pathway (hexose monophosphate shunt), generation of NADPH from glucose. Protein catabolism, the hydrolysis of proteins into amino acids. Aerobic respiration Electron transfer chain Oxidative phosphorylation Anaerobic respiration, Cori cycle Lactic acid fermentation Fermentation Ethanol fermentation Anabolism Anabolic pathways that create building blocks and compounds from simple precursors: Glycogenesis Gluconeogenesis Porphyrin synthesis pathway HMG-CoA reductase pathway, leading to cholesterol and isoprenoids. Secondary metabolism, metabolic pathways that are not essential for growth, development or reproduction, but that usually have ecological function. Photosynthesis Light-dependent reaction (light reaction) Light-independent reaction (dark reaction) Calvin cycle Carbon fixation Drug metabolism Drug metabolism pathways, the modification or degradation of drugs and other xenobiotic compounds through specialized enzyme systems: Cytochrome P450 oxidase system Flavin-containing monooxygenase system Alcohol metabolism Nitrogen metabolism Nitrogen metabolism includes the pathways for turnover and excretion of nitrogen in organisms as well as the biological processes of the biogeochemical nitrogen cycle: Urea cycle, important for excretion of nitrogen as urea. Biological nitrogen fixation Nitrogen assimilation Nitrification Denitrification Other Human iron metabolism History The first controlled experiments in human metabolism were published by Santorio Santorio in 1614 in his book Ars de statica medecina that made him famous throughout Europe. He describes his long series of experiments in which he weighed himself in a chair suspended from a steelyard balance (see image), before and after eating, sleeping, working, sex, fasting, depriving from drinking, and excreting. He found that by far the greatest part of the food he took in was lost from the body through perspiratio insensibilis (insensible perspiration). See also Metabolomics Metabolome Basal metabolic rate Thermic effect of food Iron-sulfur world theory, a "metabolism first" theory of the origin of life. Biodegradation External links Interactive Flow Chart of the Major Metabolic Pathways Metabolism, Cellular Respiration and Photosynthesis - The Virtual Library of Biochemistry and Cell Biology The Biochemistry of Metabolism at Rensselaer Polytechnic Institute Flow Chart of Metabolic Pathways at ExPASy Santorio Santorio's experiments KEGG: Kyoto Encyclopedia of Genes and Genomesth:การเผาผลาญ Search Term: "Metabolism" Categories: Metabolism

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