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 Organic + Oxygen Carbon + Water + Energy Compounds Dioxide Summary equations:

Energy Conversion Fuel rich in chemical energy Energy conversion Waste products poor in chemical energy Gasoline  Oxygen Carbon dioxide  Water Energy conversion in a car Energy for cellular work Energy conversion in a cell Heat energy Heat energy Carbon dioxide  Water Food  Oxygen Combustion Cellular respiration Kinetic energy of movement ATP

Cellular Respiration C 6 H 12 O 6 CO 2 O2O2 H2OH2O GlucoseOxygenCarbon dioxide Water  6 6 Reduction Oxidation Oxygen gains electrons (and hydrogens) Glucose loses electrons (and hydrogens) By oxidizing glucose, energy is taken out of “storage” and made available for ATP synthesis

Metabolic Disequilibrium *Multistep open hydroelectric system

3 metabolic stages: *glycolysis *Krebs cycle *electron transport chain and oxidative phosphorylation *Substrate-level phosphorylation *Oxidative phosphorylation Cellular Respiration

Cytoplasm Animal cellPlant cell Mitochondrion High-energy electrons carried by NADH High-energy electrons carried mainly by NADH Citric Acid Cycle Electron Transport Glycolysis Glucose 2 Pyruvic acid ATP Figure 6.6 Cytoplasm Animal cell Plant cell Mitochondrion High-energy electrons carried by NADH High-energy electrons carried mainly by NADH Citric Acid Cycle Electron Transport Glycolysis ATP 2 2 ~34 ~38 ATP per glucose

Glycolysis harvests chemical energy by oxidizing glucose to pyruvate. Cellular Respiration

1) Glucose is phosphorylated 2) G-6-P is rearranged 3) Addition of another phosphate group 5) Conversion b/w the 2 3-carbon sugars 4) Cleavage into 2 3-carbon sugars Cellular Respiration

6) Two components: *electron transfer *Phosphate group addition Glycolysis: Energy Payoff Phase 7) ATP production 8) Rearrangement of phosphate group 9) Loss of water 10) ATP production Cellular Respiration

Fermentation aerobic anaerobic

The Krebs cycle: energy-yielding oxidation The junction b/w glycolysis and the Krebs cycle: Multienzyme complex: 1) Removal of CO 2 2) Electron transfer *pyruvate dehydrogenase 3) Addition of CoA Cellular Respiration

The Krebs cycle: energy-yielding oxidation 1) Addition of 2 Carbons Citrate synthase 2) Isomerization Aconitase 3) *Loss of CO 2 *electron transfer Isocitrate dehydrogenase 4) *Loss of CO 2 *electron transfer  -ketoglutarate dehydrogenase 5) substrate-level phosphorylation Succinyl CoA-synthetase 6) electron transfer Succinate dehydrogenase 7) Rearrangement of bonds Fumarase 8) electron transfer Malate dehydrogenase 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 Cellular Respiration

Versatility of Cellular Respiration Food PolysaccharidesFats Proteins Sugars Glycerol Fatty acids Amino acids Glycolysis Acetyl CoA Citric Acid Cycle Electron Transport ATP – In addition to glucose, cellular respiration can “burn”: Diverse types of carbohydrates Fats Proteins