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AP BIology Ch. 8
An Introduction to Metabolism
Question | Answer |
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metabolism | The totality of an organism's chemical reactions, consisting of catabolic and anabolic pathways |
metabolic pathway | A series of chemical reactions that either builds a complex molecule (anabolic pathway) or breaks down a complex molecule into simpler compounds (catabolic pathway) |
catabolic pathway | A metabolic pathway that releases energy by breaking down complex molecules to simpler compounds |
anabolic pathway | A metabolic pathway that synthesizes a complex molecule from simpler compounds |
bioenergetics | The flow of energy through an animal, taking into account the energy stored infood it consumes, the energy used for basic functions, activity, growth, reproduction, and regulation, and the energy lost to the environment as heat or in waste |
energy | The capacity to do work (to move matter against an opposing force) |
kinetic energy | The energy of motion, which is directly related to the speed of that motion. Moving matter does work by imparting motion to other matter |
heat | The total amount of kinetic energy due to molecular motion in a body of matter. Heat is energy in its most random form. Also called thermal energy |
potential energy | The energy stored by matter as a result of its location or spatial arrangement |
chemical energy | Energy stored in the chemical bonds of molecules; a form of potential energy |
thermodynamics | The study of energy transformations that occur in a collection of matter (see 1st and 2nd laws of thermodynamics) |
first law of thermodynamics | The principle of conservation of energy. Energy can be transferred and transformed, but it cannot be created or destroyed |
entropy | A quantitative measure or randomness, symbolized by S. |
second law of thermodynamics | The principle whereby every energy transfer or transformation increases the entropy of the universe. Ordered forms of energy are at least partially converted to heat, and in spontaneous reactions, the free energy of the system also decreases |
free energy | The portion of a 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 T us absolute temperature |
exergonic reaction | A spontaneous chemical reaction, in ehich there is a net release of free energy |
endergonic reaction | A nonspontaneous chemical reaction, in which free energy is absorbed from the surroundings |
ATP (adenosine triphosphate) | An adenine-containing nucleoside triphosphate that releases free energy when its phophate bonds are hydolyzed. This energy is used to drive endergonic reactions in cells |
phosphorylated | Referring to a molecule that has been the recipient of a phosphate group |
catalyst | A chemical agent that changes the rate of a reaction without being consumed by the reaction |
enzyme | A protein serving as a catalyst, a chemical agent that changes the rate od a reaction without being consumed by the reactant |
free energy of activation | The amount of energy that reactants must abosrb before a chemical reaciton will start; also called activation energy |
substrate | The reactant on which an enzyme works |
enzyme-substrate complex | A temporary complex formed when an enzyme binds to its substrate molecule(s) |
active site | The specific portion of an enzyme that attaches to the substrate by means of weak chemical bonds |
induced fit | The change in shape of the active site of an enzyme so that it binds more snugly to the substrate, induced by entry of the substrate |
cofactor | 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 |
coenzyme | An organic molecule serving as a cofactor. Most vitamins funciton as coenzymes in important metabolic reactions. |
competitive inhibitor | A substance that reduces the activity of an enzyme by entering the active site in place of the substrate whose structure it mimics |
noncompetitive inhibitor | A substance that reduces the activity of an enzyme by binding to a location remote from the active site, changing its conformation so that is no longer binds to the substrate |
allosteric regulation | The binding of a molecule to a protein that affects the function of the protein at a different site |
cooperativity | An interaction of the consituent subunits of a protein whereby a conformational change in one subunit is transmitted to all the others |
feedback inhibition | A method of metabolic control in which the end prodcut of a metabolic pathway acts as an inhibitor of an enzyme within that pathway |