Micro303Lecture14

Aox ared aox e box e bred reduc8on poten8al

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Unformatted text preview: st also have Box Chemicals vary in their tendency to donate or accept electrons •  Can be measured and expressed for each half reac1on •  Called reduc1on poten1al (E) Box Ared Bred Aox Ared Aox +e ­ Box + e ­ Bred Reduc8on poten8al •  By conven8on, a redox half reac8on is wriTen as a reduc8on Aox + e ­ Ared •  Measure this compared to a standard reac8on to give a value For the cell: find donor and acceptor to maximize change in poten8al (ΔE) Good donors Good acceptors ΔG =  ­nFΔE (kJ) (V) ΔG = Gibbs free energy change An energy ­yielding redox reac8on Donor has a more nega8ve reduc8on poten8al Ared Box Aox Bred ΔG =  ­nFΔE Acceptor has a more posi8ve reduc8on poten8al Released free energy can be conserved by the cell Electron transfer is o[en not direct Electron carriers shuTle electrons (and some8mes protons) Ared Aox •  Small molecules –  NADH –  Quinones Box Bred •  Proteins –  Cytochromes –  Flavoproteins Nico8namide adenine dinucleo8de is a common electron shuTle in the cytoplasm Oxidized form Can accept electrons Reduced form Can donate electrons Energy storage systems capture energy released from chemical reac8ons Ared Box Aox Bred Released free energy can be conse...
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