03 etc-oxphos

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03 etc-oxphos

  1. 2. Electron Transport Chain
  2. 3. Mitochondrial Structure
  3. 4. Electron Transport Chain Overview <ul><li>The ETC removes energy stored in the NADH and FADH 2 molecules to: </li></ul><ul><li>create a proton gradient across the inner mitochondrial membrane </li></ul><ul><li>convert O 2 to H 2 O. </li></ul><ul><li>All reactions are redox reactions. </li></ul>
  4. 5. Electron Transport Chain Animation <ul><li>http://www.youtube.com/watch?v=_PgjsfY71AM </li></ul>
  5. 6. ETC Components
  6. 7. ETC Components: Complex I <ul><li>2 e - from NADH are transferred to Complex I </li></ul><ul><li>Protons are pumped across the inner mitochondrial membrane ( IMM ) by Complex I </li></ul>
  7. 8. ETC Components: Q <ul><li>e - are transferred from Complex I to ubiquinone ( Q ) </li></ul><ul><li>Q is a mobile component within the IMM </li></ul>
  8. 9. ETC Components: Complex III <ul><li>e - are transferred from Q to Complex III </li></ul><ul><li>Protons are pumped across the IMM by Complex III </li></ul>
  9. 10. ETC Components: Cyt C <ul><li>e - are transferred from Complex III to cytochrome c ( cyt c ) </li></ul><ul><li>cyt c is a mobile component on the surface of IMM, in the intermembrane space </li></ul>
  10. 11. ETC Components: Complex IV <ul><li>e - are transferred from cyt c to Complex IV </li></ul><ul><li>Protons are pumped across the IMM by Complex IV </li></ul>
  11. 12. ETC Components: O 2 <ul><li>O 2 is the final electron acceptor of the ETC </li></ul><ul><li>enough e - pass through the ETC to produce full H 2 O molecules </li></ul>
  12. 13. FADH 2 Pathway FADH 2 FAD
  13. 14. ETC Components: Complex II <ul><li>2e - are transferred from FADH 2 to Complex II </li></ul><ul><li>no protons are pumped across the IMM </li></ul><ul><li>e - are transferred from Complex II to Q and proceed through the rest of ETC </li></ul>FADH 2 FAD
  14. 15. ETC Thermodynamics <ul><li>Each electron transfer step is energetically favourable. </li></ul>
  15. 16. Electrochemical Proton Gradient Low H+ High H+
  16. 17. ETC Summary <ul><li>NADH e - transferred to O 2 ; three proton pumps activated </li></ul><ul><li>FADH 2 e - transferred to O 2 ; two proton pumps activated </li></ul><ul><li>electrochemical proton gradient formed across IMM </li></ul>
  17. 18. Electron Transport Chain Animation <ul><li>http://www.youtube.com/watch?v=_PgjsfY71AM </li></ul>
  18. 20. Proton Motive Force: Chemiosmosis <ul><li>The electrochemical gradient </li></ul><ul><li>produced by the ETC can now be used to generate ATP through the process of oxidative phosphorylation ( OXPHOS ). </li></ul><ul><li>Chemiosmosis occurs through the enzyme complex ATP synthase . </li></ul><ul><li>http://www.youtube.com/watch?v=3y1dO4nNaKY&feature=related </li></ul>
  19. 21. ATP Synthase Complex <ul><li>Two components: </li></ul><ul><li>F 0 – proton channel / rotor embedded in IMM </li></ul><ul><li>F 1 – catalytic sites that phosphorylate ADP to ATP </li></ul>
  20. 22. ATP Production <ul><li>oxidative phosphorylation - ATP is produced as protons flow through ATP synthase. </li></ul><ul><li>In general: </li></ul><ul><li>1 NADH  3 ATP molecules (how many proton pumps?) </li></ul><ul><li>1 FADH2  2 ATP molecules(how many proton pumps?) </li></ul><ul><li>The ETC is coupled with ATP synthesis. The latter is dependent on the former. </li></ul>
  21. 23. ATP Production Cellular Respiration Step Energy Molecules Produced ATP Totals Glycolysis 2 ATP 2 NADH 2 ATP special case Oxidative Decarboxylation 2 NADH 6 ATP Krebs Cycle 6 NADH 2 FADH 2 2 ATP 18 ATP 4 ATP 2 ATP
  22. 24. Glycolysis NADH <ul><li>NADH produced in glycolysis must be transported from the cytoplasm into the mitochondria to enter the ETC. </li></ul><ul><li>Two shuttle mechanisms: </li></ul><ul><li>glycerol phosphate shuttle </li></ul><ul><li>malate-aspartate shuttle </li></ul>
  23. 25. Glycerol Phosphate Shuttle 2e- from NADH get shuttled into the mitochondria and become part of FAD to become FADH 2 = 2 ATP
  24. 26. Malate-Aspartate Shuttle 2e- from NADH get shuttled into the mitochondria and become part of NAD+ to become NADH = 3 ATP
  25. 27. ATP Production Summary Cellular Respiration Step Energy Molecules Produced ATP Totals Glycolysis 2 ATP 2 NADH 2 ATP 4-6 ATP Oxidative Decarboxylation 2 NADH 6 ATP Krebs Cycle 6 NADH 2 FADH 2 2 ATP 18 ATP 4 ATP 2 ATP TOTAL 36-38 ATP
  26. 28. Glycolysis
  27. 29. Oxidative Decarboxylation <ul><li>Pyruvate is converted into acetyl-CoA in order to be brought into the mitochondria. </li></ul>
  28. 30. Krebs Cycle

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