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Oxidative Phosphorylation
mitochondria (stained green), form a network inside a fibroblast cell.
Mitochondria oxidize C fuel to form cellular energy in form of ATP.
• Oxidative phosphorylation: formation of ATP as a result of the transfer of
electrons from NADH or FADH2 to O2
• - coupled by a proton gradient across the inner mitochondrial membrane.
• - culmination of a series of energy transformation (cellular respiration);
generates 26 of 30 ATP/glucose oxidation to CO2
Oxidative phosphorylation couples the oxidation of C fuels
to ATP synthesis with a H gradient
• Oxidation and ATP synthesis coupled by transmembrane proton fluxes
Oxidative Phosphorylation in Eukaryotes Occurs in
Mitochondria
• Mitochondria contain: respiratory assembly, enzymes of the citric acid cycle,
and enzymes of fatty acid oxidation.
Mitochondria are the result of an endosymbiotic event
•Sizes of mitochondrial genomes: red for genes with known function
•Rickettsia: relative of presumed ancestor of all mitochondria
Oxidative phosphorylation depends on electron transfer
High energy electrons: redox potentials and free-energy changes
• Electron transfer potential of NADH is converted into phosphoryl transfer
potential of ATP.
• Electron transfer potential : Reduction potential, redox potential, oxidation
reduction potential.
•The reduction potential of the X: X- couple (redox couple) is the observed
voltage at the start of the experiment.
•Measurement of redox potential: e, but not X or X-, can flow through the agar
bridge.
• Apparatus for measurement of the standard oxidation-reduction potential of a
redox couple