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Electron Transport Chain

Electron Transport Chain. Filename: ETChain.ppt. Lecture Outline. Using Chemical energy to drive metabolism Production of ATP Cellular respiration Clycolysis Krebs cycle Electron transport Chemiosmosis. Lecture Overview. All organisms drive their metabolism with ATP generated from

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Electron Transport Chain

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  1. Electron Transport Chain Filename: ETChain.ppt

  2. Lecture Outline • Using Chemical energy to drive metabolism • Production of ATP • Cellular respiration • Clycolysis • Krebs cycle • Electron transport • Chemiosmosis

  3. Lecture Overview • All organisms drive their metabolism with ATP generated from • Rearrangement of chemical bonds • Energetic electrons from proton pumps • Electrons from photosynthesis • Electrons from oxidation of sugars and fats

  4. Cellular Respiration • Release of energy stored in organic compounds • Carbohydrate • Fats • Proteins (net energy loss) • Oxygen is consumed as a reactant • Carbon dioxide and water are byproducts • Energy is used indirectly • trapped as ATP

  5. Pathways in Cellular Respiration • Glycolysis • Krebs cycle • Electron transport chain Cellular Respiration Cumulative function of three metabolic pathways and chemiosmosis

  6. Catabolism of various foods

  7. Overview of Cellular Respiration A room of your own... ATP ATP ATP

  8. Electron Transport System

  9. IN Out IN IN Out Out Out IN Summary of Krebs Cycle

  10. Large Free energy drop ( 53 kcal/mol) is broken into a series of smaller steps that release energy in manageable amounts Electron Transport Chain • OCCURS in MITOCHONDRIAL INNER MEMBRANE or PROKARYTOIC CELL MEMBRANE • linked to Glycolysis and Krebs cycle • Electrons passed from NADH to oxygen • Does not make ATP directly but through chemiosmosis

  11. Oxidation is the loss of electrons to any electron acceptor Although oxygen is the usual electron acceptor other electron acceptors include NAD+

  12. NADH as an Electron Shuttle Reduction Oxidation NADH Nicotinamide-adenine dinucleotide

  13. Electron Transport Chain

  14. ATP ATP ATP ATP How ATP Drives Cellular Work

  15. 2 Ways to Produce ATP • Substrate level phosphorylation • produces few molecules of ATP in aerobes (2 ATP from the respiration of 1 molecule of glucose) • Proton motor force (chemiosmosis) • produces most of the ATP in aerobes (about 30 ATP from the complete respiration of glucose to CO2 and H2O)

  16. Substrate Level PhosphorylationATP Production • more primitive methodExamples: 2 steps in glycolysis where • ADP + Substrate-P -> ATP + substrate • Note that the phosphate comes from a phosphorylated substrate, not from Pi • 2 ADP + Phosphoenolpyruvate -> pyruvate + 2 ATP

  17. Proton Motor ForceATP production ATP synthase/ FoF1 complex • More advanced method • Proton transport across a membrane with FoF1 complex powers the following reaction:- • ADP + Pi -> ATP • Note that the phosphate comes from Pi(inorganic phosphate) • This is the major ATP source for aerobic bacteria, mitochondria and chloroplasts

  18. ATP synthase/ FoF1 complex requires: • Membrane • Gradient of H+ concentration across membrane (one side more acid than the other) • Fo/Fi protein complex in membrane • ADP + Pi

  19. + H ADP • +Pi + + + H + H H + H + H + H + H + H H FoF1 complex ATP F1 Membrane Fo low pH

  20. + H + + H H + + H H FoF1 complex ADP ATP • +Pi F1 (9 protein subunits) carries ATP synthase Fo (3 subunits in bacteria) forms a proton channel

  21. F1 FoF1 complexes under EM look like “lollipops” F1 F1 Fo Fo Fo

  22. F1 F1 + H + + F1 H H Fo Shows proton transfer + H Dissociated FoF1 Shows only ATP’ase Fo

  23. FOF1 COMPLEXES Aerobic bacterium = acid region matrix Mitochondrion Chloroplast stroma thylakoid

  24. How does the FoF1 complex work? Not known ? F1 Fo One hypothesis is that F1 rotates as it releases ATP’s

  25. Chemiosmosis proton motor force chemical energy ATP

  26. Review Tally=2 Tally=2 Tally=0 Tally= ~36

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