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L15_2009 Bioenergetics II Oxidative phosphorylation - fermentation

Steps split off 2 co2 phosphorylate adp repeat the

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Unformatted text preview: cle kJ reduce 3 NAD FAD 400 -1000 -2000 But most of the energy stored as electron energy in reduced dinucleotides, not as ATP -3000 MITOCHONDRION Where we’re going 1. Oxidative phosphorylation a. Electron transport chain b. Chemiosmosis 2. Fermentation 3. Energy from fats matrix outer membrane inner membrane OXIDATIVE PHOSPHORYLATION Electron Transport Chain H2 + 1/2 O2 200 Free energy (G) relati ve to O2 (kJ/mol e) Free energy, G Electron transport chain is a series of proton pumps 160 120 80 40 series of downhill redo x reactions G = - 241.6 kJ/mole H2O 0 Electron transport chain Still no ATP THE MYSTERY OF ATP SYNTHESIS Efriam Racker (~1960): Substrate level phosphorylation seemed to account for all of the ATP synthesis in the cell. A Radical Solution: Chemiosmotic Hypothesis A theory, proposed in 19611, that ATP synthesis in cells comes not from substrate-level phosphorylation, but rather from the establishment of an electro-chemical gradient across the inner membrane of the mitochondrion using energy from NADH and FADH2 formed from the breakdown of molecules such as glucose. Problems: Where were the high-energy intermediate molecules? Why were the enzymes always associated with the mitochondrial membrane? Why was ATP synthesis so dependent upon maintaining the mitochondrial structure? “Progress is made by young scientists who carry out experiments that old scient...
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