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5/3/2013 Cellular Respiration Cellular respiration: A catabolic energy yielding pathway in which oxygen and organic fuels are consumed and ATP is produced • An aerobic process—it requires oxygen Summary equations: Organic Compounds + Oxygen Carbon + Water Dioxide + Energy Energy Conversion Fuel rich in chemical energy Waste products poor in chemical energy Energy conversion Heat energy Gasoline + Carbon dioxide + Combustion Kinetic energy of movement Energy conversion in a car Oxygen Water Heat energy Cellular respiration Food + Carbon dioxide + ATP Energy for cellular work Oxygen Water Energy conversion in a cell Cellular Respiration •By oxidizing glucose, energy is taken out of “storage” and made available for ATP synthesis Oxidation Glucose loses electrons (and hydrogens) C6H12O6 Glucose + 6 O2 Oxygen 6 CO2 Carbon dioxide + 6 H2O Water Reduction Oxygen gains electrons (and hydrogens) 1 5/3/2013 Metabolic Disequilibrium *Multistep open hydroelectric system Cellular Respiration *Substrate-level phosphorylation 3 metabolic stages: *glycolysis *Krebs cycle *Oxidative phosphorylation *electron transport chain and oxidative phosphorylation Mitochondrion Cytoplasm Cytoplasm Plant cell Animal cell Animal cell Plant cell Cytoplasm Cytoplasm High-energy High-energy electrons electrons carried carried NADH bybyNADH Glycolysis Glycolysis2 Glucose Pyruvic acid 2 ATP ATP Mitochondrion Mitochondrion High-energy High-energy electrons carried electrons carried mainly mainlyby by NADH NADH Citric Citric Electron Acid Electron Acid Transport Cycle Transport Cycle 2 ATP ATP ~34 ATP ATP ~38 ATP per glucose Figure 6.6 2 5/3/2013 Cellular Respiration Glycolysis harvests chemical energy by oxidizing glucose to pyruvate. Cellular Respiration 1) Glucose is phosphorylated 3) Addition of another phosphate group 4) Cleavage into 2 3-carbon sugars 2) G-6-P is rearranged 5) Conversion b/w the 2 3-carbon sugars Cellular Respiration 6) Two components: *electron transfer *Phosphate group addition Glycolysis: Energy Payoff Phase 9) Loss of water 7) ATP production 8) Rearrangement of phosphate group 10) ATP production 3 5/3/2013 Fermentation aerobic anaerobic The Krebs cycle: energy-yielding oxidation Cellular Respiration The junction b/w glycolysis and the Krebs cycle: Multienzyme complex: 1) Removal of CO2 2) Electron transfer *pyruvate dehydrogenase 3) Addition of CoA Cellular Respiration The Krebs cycle: energy-yielding oxidation 8) electron transfer Malate dehydrogenase 1) Addition of 2 Carbons Citrate synthase 2) Isomerization Aconitase 7) Rearrangement R t of bonds Fumarase 6) electron transfer Succinate dehydrogenase 3) *Loss of CO2 **electron transfer f Isocitrate dehydrogenase 4) *Loss of CO2 *electron transfer α-ketoglutarate dehydrogenase 5) substrate-level phosphorylation Succinyl CoA-synthetase 4 5/3/2013 Cellular Respiration Electron transport and ATP synthesis *Multi-step open system Cellular Respiration Generation and maintenance of an H+ gradient *Exergonic flow of e-, pumps H+ across the membrane *chemiosmosis high energy electrons Cellular Respiration *How does the mitochondrion couple electron transport and ATP synthesis? ATP synthase 5 5/3/2013 Versatility of Cellular Respiration – In addition to glucose, cellular respiration can “burn”: • Diverse types of carbohydrates • Fats Food • Proteins Polysaccharides Fats Sugars Glycerol Fatty acids Glycolysis Acetyl CoA Proteins Amino acids Citric Acid Cycle Electron Transport ATP 6