CH 14 - Chapter 14 Energy generation in mitochondria and chloroplasts 14_05_generate_energy mitochondrial matrix 1 Energy released during passage

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10/7/09 1 Chapter 14 Energy generation in mitochondria and chloroplasts 14_05_generate_energy.jpg mitochondrial matrix
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10/7/09 2 Energy released during passage of electrons through the electron-transport chain is harnessed to pump protons across the mitochondrial inner membrane - How does this work? NAD + is regenerated O 2 is the terminal electron acceptor Reductions often involve the transfer of a proton (charge neutralization) The orientation of electron carrier complexes in the membrane allows release of the proton to the opposite face of the membrane when the electron is released (oxidation)
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10/7/09 3 The energy released by electron transfer can be quantified Redox Potential See Panel 14-1 Oxidation-reduction (redox) reactions proceed depending on Δ G just like any other chemical reaction. Standard redox potentials (E 0 ’) are also defined in a way similar to Δ G o Reduced and Oxidized molecules are equimolar, pH is 7.0 Compared to a reference (2H + + 2e - H 2 ) The voltage difference (compared to the reference) is measured Compounds with negative redox potentials have low affinity for electrons and are likely to donate them (NADH, E 0 ’= -320 mV) Electrons flow to more positive redox potentials, releasing energy Δ G o = -nF Δ E 0 Each step of the electron-transport chain has a more positive redox potential so the direction of electron flow is constant and energy is harnessed at each step until the terminal electron acceptor is reached: O 2 + 4H + + 4e - H 2 O E 0 ’= +820 mV
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10/7/09 4 Electrons are transferred to tightly bound metal atoms within
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This note was uploaded on 04/09/2010 for the course BIOL 213 taught by Professor Mcknight during the Spring '07 term at Texas A&M.

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CH 14 - Chapter 14 Energy generation in mitochondria and chloroplasts 14_05_generate_energy mitochondrial matrix 1 Energy released during passage

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