Lecture 12 Oxidative Phosphorylation

Lecture 12 Oxidative Phosphorylation - Electron Transport...

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Unformatted text preview: Electron Transport and Oxidative Phosphorylation Stryer Chapter 18 Mitochondria Electron transfer Proton pumps/Proton gradient Movement across membranes Regulation 1 The TCA cycle, electron transport, and oxidative phosphorylation occur in the mitochondria - the energy generators of the cell Outer membrane is permeable to small molecules Inner membrane is not - ATP, pyruvate, and citrate are transported specifically ~ 2 m x 0.5 m 2 Overview of Oxidative Phosphorylation 3 NADH and FADH 2 pass their electrons to O 2 to produce H 2 O and by doing so, create a proton gradient used for Oxidative-Phosphorylation I II III IV 4 Redox Potentials are related to G G = -RT ln K eq pH = 7 G = -n F E = -RT ln K eq pH = 7 G = -n(23 kcal/mol/V) E X red + H + ==> X ox + 1/2 H 2 X red ==> X ox + e H + + e ==> 1/2 H 2 E = Standard reduction potential at pH 7.0 and 25 C (oxidant + e- reductant) E = Change in the standard reduction potential F = Faraday constant = 23.06 kcal mol-1 V-1 n = number of electrons 5 A Theoretical Electrochemical Cell for Measuring Standard Redox Potentials Allows ions to cross for electrical flow 6 7 Calculating G for a reaction Pyruvate + NADH + H + <==> Lactate + NAD + Pyruvate + 2 H + + 2 e ==> Lactate E = 0.19 V NAD + + H + + 2 e ==> NADH E = 0.32 V NADH ==> NAD + = H + + 2 e E = + 0.32 V Therefore: Pyruvate + NADH + H + <==> Lactate + NAD + E = + 0.13 V G = n F E pH = 7 G = n(23 kcal/mol/V) E = 2(23 kcal/mol/V)(0.13V) = 6 kcal/mol 8 Energy-rich NADH passes electrons down an energy gradient into complexes with energy differences useful for synthesizing ATP I II III IV 9 Flavin mononucleotide (FMN) FMN functions similarly to FAD; both can be in oxidized, reduced, or semiquinone (1 e ) states 10 Coenzyme Q is an important electron carrier in the mitochondrial membrane Coenzyme Q can also exist in 3 redox states: Oxidized (ubiquinone), a partially reduced semiquinone intermediate, and fully reduced (ubiquinol)....
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Lecture 12 Oxidative Phosphorylation - Electron Transport...

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