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| Drives the cellular economy by extracting the energy stored in sugars and other fuels. |
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| The totality of an organism’s chemical reactions,consisting of catabolic and anabolic pathways, which manage the material and energy resources of the organism. |
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A series of chemical reactions that either builds a complex molecule (anabolic pathway) or breaks down a complex molecule into simpler compounds (catabolic pathway). |
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| A metabolic pathway that releases energy by breaking down complex molecules to simpler compounds. |
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| A metabolic pathway that consumes energy to synthesize a complex molecule from simpler compounds. |
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The capacity to cause change, especially to do work (to move matter against an opposing force). |
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| The energy associated with the relative motion of objects. Moving matter can perform work by imparting motion to other matter. |
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The total amount of kinetic energy due to the random motion of atoms or molecules in a body of matter; also called thermal energy. Heat is energy in its most random form. |
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See heat The total amount of kinetic energy due to the random motion of atoms or molecules in a body of matter; also called thermal energy. Heat is energy in its most random form. |
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The energy that matter possesses as a result of its location or spatial arrangement (structure). |
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Energy available in molecules for release in a chemical reaction; a form of potential energy. |
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| The study of energy transformations that occur in a collection of matter. See first law of thermodynamics; second law of thermodynamics. |
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| first law of thermodynamics |
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The principle of conservation of energy: Energy can be transferred and transformed, but it cannot be created or destroyed. |
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second law of thermodynamics |
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The principle stating that every energy transfer or transformation increases the entropy of the universe. Ordered forms of energy are at least partly converted to heat. |
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A measure of disorder, or randomness. |
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The portion of a biological system’s energy that can perform work when temperature and pressure are uniform throughout the system. (The change in free energy of a system is calculated by the equation ΔG = ΔH – TΔS, where H is enthalpy [in biological systems, equivalent to total energy], T is absolute temperature, and S is entropy.) |
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(ek´-ser-gon´-ik) A spontaneous chemical reaction, in which there is a net release of free energy. |
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(en´-der-gon´-ik) A nonspontaneous chemical reaction, in which free energy is absorbed from the surroundings. |
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In cellular metabolism, the use of energy released from an exergonic reaction to drive an endergonic reaction. |
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ATP (adenosine triphosphate) |
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| a-den´-o-sen tri fos´-fat) An adenine-containing nucleoside triphosphate that releases free energy when its phosphate bonds are hydrolyzed. This energy is used to drive endergonic reactions in cells. |
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Referring to a molecule that is covalently bonded to a phosphate group. |
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| A macromolecule serving as a catalyst, a chemical agent that changes the rate of a reaction without being consumed by the reaction. |
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| A chemical agent that increases the rate of a reaction without being consumed by the reaction. |
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The amount of energy that reactants must absorb before a chemical reaction will start; also called free energy of activation. |
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The reactant on which an enzyme works. |
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A temporary complex formed when an enzyme binds to its substrate molecule(s). |
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Induced by entry of the substrate, the change in shape of the active site of an enzyme so that it binds more snugly to the substrate. |
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Any nonprotein molecule or ion that is required for the proper functioning of an enzyme. Cofactors can be permanently bound to the active site or may bind loosely with the substrate during catalysis. |
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| An organic molecule serving as a cofactor. Most vitamins function as coenzymes in metabolic reactions. |
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A substance that reduces the activity of an enzyme by entering the active site in place of the substrate whose structure it mimics. |
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A substance that reduces the activity of an enzyme by binding to a location remote from the active site, changing the enzyme’s shape so that the active site no longer functions effectively. |
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The binding of a regulatory molecule to a protein at one site that affects the function of the protein at a different site. |
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A kind of allosteric regulation whereby a shape change in one subunit of a protein caused by substrate binding is transmitted to all the others, facilitating binding of subsequent substrate molecules. |
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A method of metabolic control in which the end product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway. |
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