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Information about Catabolism

For the related metabolic process, see anabolism.


Catabolism is the set of metabolic pathways that break down molecules into smaller units and release energy. In catabolism, large molecules such as polysaccharides, fatty acids, 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 that 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 that 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

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Metabolism
Catabolism - Anabolism Metabolic pathway - Metabolic network - Cellular respiration (Anaerobic/Aerobic) Protein metabolism - Carbohydrate metabolism - Lipid metabolism - Iron metabolism
Anabolism is the set of metabolic pathways that construct molecules from smaller units. These reactions require energy. One way of categorizing metabolic processes, whether at the cellular, organ or organism level is as 'anabolic' or 'catabolic', which is the opposite.
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In biochemistry, a metabolic pathway is a series of chemical reactions occurring within a cell. In each pathway a principal chemical is modified by chemical reactions. These reactions are accelerated, more accurately catalyzed, by enzymes.
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energy (from the Greek ενεργός, energos, "active, working")[1] is a scalar physical quantity that is a property of objects and systems of objects which is conserved by nature.
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Polysaccharides are relatively complex carbohydrates. They are polymers made up of many monosaccharides joined together by glycosidic bonds. They are therefore very large, often branched, macromolecules. They tend to be amorphous, insoluble in water, and have no sweet taste.
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Types of Fats in Food
  • Unsaturated fat
  • Monounsaturated fat
  • Polyunsaturated fat
  • Trans fat
  • Omega: 3, 6, 9

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A nucleic acid is a macromolecule composed of nucleotide chains. In biochemistry these molecules carry genetic information or form structures within cells. The most common nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
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Proteins are large organic compounds made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid residues.
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Monosaccharides (from Greek : single, sacchar: sugar) are the simplest carbohydrates. They cannot be hydrolyzed into simpler sugars. They consist of one sugar and are usually colorless, water-soluble, crystalline solids. Some monosaccharides have a sweet taste.
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Types of Fats in Food
  • Unsaturated fat
  • Monounsaturated fat
  • Polyunsaturated fat
  • Trans fat
  • Omega: 3, 6, 9

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A nucleotide is a chemical compound that consists of 3 portions: a heterocyclic base, a sugar, and one or more phosphate groups. In the most common nucleotides the base is a derivative of purine or pyrimidine, and the sugar is the pentose (five-carbon sugar) deoxyribose or ribose.
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amino acid is a molecule that contains both amine and carboxyl functional groups. In biochemistry, this term refers to alpha-amino acids with the general formula H2NCHRCOOH, where R is an organic substituent.
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A monomer (from Greek mono "one" and meros "part") is a small molecule that may become chemically bonded to other monomers to form a polymer.

Examples of monomers are hydrocarbons such as the alkene and arene homologous series.
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polymer is a substance composed of molecules with large molecular mass composed of repeating structural units, or monomers, connected by covalent chemical bonds. The word is derived from the Greek, πολυ, polu, "many"; and μέρος, meros,
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A monomer (from Greek mono "one" and meros "part") is a small molecule that may become chemically bonded to other monomers to form a polymer.

Examples of monomers are hydrocarbons such as the alkene and arene homologous series.
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Lactic acid (IUPAC systematic name: 2-hydroxypropanoic acid), also known as milk acid, is a chemical compound that plays a role in several biochemical processes.
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Acetic acid, also known as ethanoic acid, is an organic chemical compound best recognized for giving vinegar its sour taste and pungent smell. Its structural formula is represented as CH3COOH.
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Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state.
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Ammonia is a compound with the formula NH3. It is normally encountered as a gas with a characteristic pungent odor. Ammonia contributes significantly to the nutritional needs of the planet as a precursor to foodstuffs and fertilizers.
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Urea is an organic compound with the chemical formula (NH2)2CO.

Urea is also known as carbamide, especially in the recommended International Nonproprietary Names (rINN) in use in Europe.
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Redox (shorthand for reduction/oxidation reaction) describes all chemical reactions in which atoms have their oxidation number (oxidation state) changed.

This can be either a simple redox process such as the oxidation of carbon to yield carbon dioxide, or the
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Adenosine 5'-triphosphate (ATP) is a multifunctional nucleotide that is most important as a "molecular currency" of intracellular energy transfer. In this role, ATP transports chemical energy within cells for metabolism.
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Anabolism is the set of metabolic pathways that construct molecules from smaller units. These reactions require energy. One way of categorizing metabolic processes, whether at the cellular, organ or organism level is as 'anabolic' or 'catabolic', which is the opposite.
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Embden-Meyerhof pathway, initially explained by Gustav Embden and Otto Meyerhof. The term can be taken to include alternative pathways, such as the Entner-Doudoroff Pathway. However, glycolysis will be used here as a synonym for the Embden-Meyerhof pathway.
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citric acid cycle, also known as the tricarboxylic acid (TCA) cycle, the Krebs cycle, or Szent-Györgyi-Krebs cycle (after Hans Adolf Krebs and Albert Szent-Györgyi who first determined the chemical intermediates and reaction sequence of the cycle), is a series
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In biochemistry, a substrate is a molecule upon which an enzyme acts. Enzymes catalyze chemical reactions involving the substrate(s). The substrate binds with the enzyme's active site, and an enzyme-substrate complex is formed.
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Gluconeogenesis is the generation of glucose from non-sugar carbon substrates like pyruvate, lactate, glycerol, and glucogenic amino acids (primarily alanine and glutamine).
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Fat

Fat may refer to:
  • Fat, a group of compounds that are generally soluble in organic solvents and largely insoluble in water
  • Adipose tissue, an anatomical term for loose connective tissue composed of adipocytes

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adipose tissue or fat is loose connective tissue composed of adipocytes. Its main role is to store energy in the form of fat, although it also cushions and insulates the body.
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Types of Fats in Food
  • Unsaturated fat
  • Monounsaturated fat
  • Polyunsaturated fat
  • Trans fat
  • Omega: 3, 6, 9

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