ETSslides - Electron Transport and Electron Transport and...

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Unformatted text preview: Electron Transport and Electron Transport and Oxidative Phosphorylation Oxidative Phosphorylation -- Introduction Introduction most energy from fuel is obtained through these oxidative processes fuel + O 2 energy oxidation -transfer of electrons to acceptor- aerobic acceptor = oxygen-- Efficient Efficient-- very efficient process- recall living cells efficiency is ~ 42%, compared to about 3% efficiency when burning oil or gasoline HOW?-- Separating carbohydrates, lipids, etc. from oxygen to optimize recover of energy-- STEPWISE -- NADH and FADH 2 made available during respiration for oxidation to generate ATP ******************************************* Questions Questions How is the energy to synthesize ATP obtained in respiration? How is the energy yield maximized? Mitochondrion Mitochondrion-- A. football shaped (1-2 ), 1-1000s in each cell B. electron transport and oxidative phosphorylation Cytosol C. Outer membrane- permeableto small molecules D. Inner membrane- electron transport enzymes embedded; also ATP synthase Cristae increase area Impermeable to small molecules Integrity required for coupling ETS to ATP synthesis Cytosol E. Matrix TCA enzymes, other enzymes; also ATP, ADP, NAD, NADH, Mg 2+ , etc. Definitions: Oxidation Definitions: Oxidation-- Reduction Reduction = transfer of electrons from electron donor to electron acceptor Example: A:H + B = A + B:H donor acceptor electron donor (reducing agent, reductant) is itself oxidized electron acceptor (oxidizing agent, oxidant) is itself reduced-- both oxidation and reduction must occur simultaneously--one compound donates electrons to (reduces) a second compound; the second accepts electrons from (oxidizes) the first. Redox /oxidation-reduction-- electrons always move from compounds with lower reduction potential to compounds with higher reduction potential ( more positive). Biological Biological redox redox = Two half-reactions A:H A Reductant ' oxidant + e- B B:H Oxidant + e- ' reductant (acceptor) (donor) Standard reduction potential, E -- measure of the tendency of oxidant to gain electrons, to become reduced, a potential energy. *********************************************************** So, the more negative the reduction potential is, the easier a reductant can reduce an oxidant and The more positive the reductive potential is, the easier an oxidant can oxidize a reductant The difference in reduction potential must be important ************************************************************ Reduction Potential Difference = Reduction Potential Difference = E E E = E (acceptor) - E (donor) measured in volts. The more positive the reduction potential difference is, the easier the redox reaction Work can be derived from the transfer of electrons and the ETS can be used to synthesize ATP. The reduction potential can be related to free energy change by: G = -n F E where n = # electrons transferred = 1,2,3 F = 96.5 kJ/volt, called the Faraday constant ********************************************************************...
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This note was uploaded on 06/07/2011 for the course BCH 4024 taught by Professor Allison during the Fall '08 term at University of Florida.

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ETSslides - Electron Transport and Electron Transport and...

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