09 - CHAPTER9 Aerobic Metabolism I: The Citric Acid Cycle...

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Biochemistry: The Molecular Basis of Life, 4/e McKee/McKee Copyright © 2009 by Oxford University Press, Inc. C H A P T E R 9 Aerobic Metabolism I: The Citric Acid Cycle
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Overview FIGURE 9.2 Aerobic Metabolism in the Mitochondrion FIGURE 9.1 Overview of Aerobic Metabolism Rise of O 2 in Earth’s atmosphere due to cyanobacteria (2.7-2 By) ! new chemical realities for cells: - highly potent oxidant (e - acceptor) - ROS - less radiation due to O 3 layer. Organisms in relation to O 2 : - anaerobies: obligate (aerotolerant & intolerant) and facultative - aerobes: obligate and facultative Aerobic metabolism : - citric acid cycle (Krebs cycle, tricarboxylic acid cycle, TCA) [burning acetate into CO 2 and generating NADH] - electron transport chains [using reductive potential of electrons to pump H + across the membrane] - ATP synthesis [using the energy of H + gradient to make ATP] Mitochondrion (bacterial symbiont) – aerobic power generator.
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9.1 Oxidation-reduction reactions Energy-capturing and energy-releasing pathways involve redox reactions (e - transfer). Cu + + Fe 3+ Cu 2+ + Fe 2+ Cu + Cu 2+ + e - half-rxns Fe 3+ + e - Fe 2+ Reduction potential, E = tendency to gain electrons. Standard reduction potential, E° , is measured against standard H 2 electrode under standard conditions. 2H + + 2 e - H 2 Standard conditions (1 M conc., 25°C, 1 atm): = 0 V. pH 7 (reference H 2 electrode): = -0.42 V (against standard H 2 electrode). Standard reduction potentials of redox half-rxns (written to have a reducing agent to the right): 2H + + 2e - ! H 2 -0.42 pyruvate + 2H + + 2e - ! lactate -0.19 Cu 2+ + e - !
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This note was uploaded on 10/15/2010 for the course MOLB 3610 taught by Professor Gomelsky during the Fall '10 term at Univeristy of Wyoming- Laramie.

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09 - CHAPTER9 Aerobic Metabolism I: The Citric Acid Cycle...

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