Clicker Question #1

1. Clicker Question #1 • 1. What compound directly provides energy for cellular work? • A. DNA • B. C6H12O6 • C. glucose • D. ATP • E. fat

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

3. Cellular Respiration Organic + Oxygen Carbon + Water + Energy Compounds Dioxide • 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:

4. Cellular Respiration •By oxidizing glucose, energy is taken out of “storage” and made available for ATP synthesis Oxidation Glucose loses electrons (and hydrogens)  6 6 H2O  6 C6H12O6 O2 CO2 Glucose Oxygen Carbon dioxide Water Reduction Oxygen gains electrons (and hydrogens)

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

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

7. *Multi-step open system Metabolic Disequilibrium

8. Glycolysis harvests chemical energy by oxidizing glucose to pyruvate

9. 4) Cleavage into 2 3-carbon sugars Glycolysis: Energy Investment Phase 3) Addition of another phosphate group 1) Glucose is phosphorylated 2) G-6-P is rearranged 5) Conversion b/w the 2 3-carbon sugars

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

11. aerobic anaerobic Fermentation enables cell to produce ATP w/o O2 *Fermentation generates ATP by substrate-level phosphorylation

12. aerobic anaerobic The presence or absence of O2 dictates the fate of pyruvate

13. The Krebs cycle: energy-yielding oxidation The junction b/w glycolysis and the Krebs cycle: Multienzyme complex: 1) Removal of CO2 2) Electron transfer *pyruvate dehydrogenase 3) Addition of CoA

14. The Krebs cycle: energy-yielding oxidation 8) electron transfer Malate dehydrogenase 1) Addition of 2 Carbons Citrate synthase 2) Isomerization Aconitase 3) *Loss of CO2 *electron transfer Isocitrate dehydrogenase 7) Rearrangement of bonds Fumarase 4) *Loss of CO2 *electron transfer a-ketoglutarate dehydrogenase 6) electron transfer Succinate dehydrogenase 5) substrate-level phosphorylation Succinyl CoA-synthetase

15. *Multi-step open system Electron transport and ATP synthesis

16. Generation and maintenance of an H+ gradient *Exergonic flow of e-, pumps H+ across the membrane *chemiosmosis high energy electrons

17. ATP synthase *How does the mitochondrion couple electron transport and ATP synthesis?

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