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Unformatted text preview: Bioenergetics Objectives-Review First and Second Laws of Thermodynamics. -Be able to use G as an index as to whether such reactions proceed spontaneously. -Know and be able to use the equation that relates the change in standard free energy ( G o ) and the equilibrium constant (Keq). -Distinguish between G and G o : Know and be able to use the equation that relates them-Define "coupled reactions" -Understand the concept of the "high-energy" bond (i.e., a bond with high group transfer potential, energy released upon hydrolysis). -Be able to indicate which bonds in ATP and other molecules have high group transfer potential and to explain the chemical basis for this. -Be able to describe in what form "reducing power" is captured and temporarily stored -Be able to use standard reduction potential values to predict the direction of oxidation- reduction reactions I. Overview Bioenergetics is the study of how biological systems interconvert energy Photosynthetic organisms Nonphotosynthetic organisms Living organisms are far from thermodynamic equilibrium, i.e. they have much lower entropy than their environment. Biological systems must obtain E from an external source and change the form of the energy into something that is usable for their own metabolic processes. For most organisms the source of immediately usable biological energy is ATP. . z of thermodynamics e First Law: Energy is Conserved B. Second Law: Entropy Increases III Free Energy . G exergonic G is negative endergonic , G is positive Free energy graph What is G made up of? Enthalpy: H is negative when a chemical reaction releases heat, Favorable Entropy: S = randomness of the system; disorder. When a reaction ends up with more disordered products (less complex), then the reaction has a gain in entropy, and S is positive. Favorable G = , S B. G o At standard biochemical conditions (pH, water) IV Reaction thermodynamics Energy difference between reactants and products Keq At equilibrium the [products] does not necessarily equal the [reactants]....
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This note was uploaded on 04/05/2008 for the course BIOCHEM 423 taught by Professor Osgood during the Spring '08 term at New Mexico.
- Spring '08