An Introduction to Metabolism

activation energy
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Terms in this set (36)
cofactorAny 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.competitive inhibitorA substance that reduces the activity of an enzyme by entering the active site in place of the substrate whose structure it mimics.cooperativityA 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.endergonic reactionA nonspontaneous chemical reaction, in which free energy is absorbed from the surroundings.energyThe capacity to cause change, especially to do work (to move matter against an opposing force).energy couplingIn cellular metabolism, the use of energy released from an exergonic reaction to drive an endergonic reaction.entropyA measure of disorder, or randomness.enzymeA macromolecule serving as a catalyst, a chemical agent that changes the rate of a reaction without being consumed by the reaction.enzyme-substrate complexA temporary complex formed when an enzyme binds to its substrate molecule(s).exergonic reactionA spontaneous chemical reaction, in which there is a net release of free inhibitionA method of metabolic control in which the end product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway.first law of thermodynamicsThe principle of conservation of energy: Energy can be transferred and transformed, but it cannot be created or energyThe 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 ?G = ?H - T?S, where H is enthalpy [in biological systems, equivalent to total energy], T is absolute temperature, and S is entropy.)heatThe 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.hemoglobinAn iron-containing protein in red blood cells that reversibly binds oxygen.induced fitInduced 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.kinetic energyThe energy associated with the relative motion of objects. Moving matter can perform work by imparting motion to other matter.metabolic pathwayA series of chemical reactions that either builds a complex molecule (anabolic pathway) or breaks down a complex molecule into simpler compounds (catabolic pathway).metabolismThe totality of an organism's chemical reactions, consisting of catabolic and anabolic pathways, which manage the material and energy resources of the organism.noncompetitive inhibitorA 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.phosphorylatedReferring to a molecule that is covalently bonded to a phosphate group.potential energyThe energy that matter possesses as a result of its location or spatial arrangement (structure).riboseThe sugar component of RNA nucleotides.second law of thermodynamicsThe 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.substrateThe reactant on which an enzyme works.thermodynamicsThe study of energy transformations that occur in a collection of matter. See first law of thermodynamics; second law of thermodynamics.