2. AP Biology 2006-2007 Cellular Respiration Stage 4: Electron Transport Chain

3. AP Biology Cellular respiration

4. AP Biology 2006-2007 What’s the point? The point is to make ATP ! ATP

5. AP Biology ATP accounting so far…  Glycolysis  2 ATP (substrate level phosphorylation)  Kreb’s cycle  2 ATP (substrate level phophorylation)  Life takes a lot of energy to run, need to extract more energy than 4 ATP! A working muscle recycles over 10 million ATPs per second There’s got to be a better way! I need a lot more ATP!

6. AP Biology There is a better way!  Electron Transport Chain  series of proteins built into inner mitochondrial membrane  along cristae  transport of electrons down ETC linked to pumping of H + to create H + gradient  yields ~34 ATP from 1 glucose!  only in presence of O 2 (aerobic respiration)  Oxidative phosphorylation O2O2

7. AP Biology  http://www.youtube.com/watch?feature =endscreen&v=kN5MtqAB_Yc&NR=1 http://www.youtube.com/watch?feature =endscreen&v=kN5MtqAB_Yc&NR=1  http://highered.mcgraw- hill.com/sites/dl/free/0072437316/12006 0/ravenanimation.html http://highered.mcgraw- hill.com/sites/dl/free/0072437316/12006 0/ravenanimation.html

8. AP Biology Electron Transport Chain Intermembrane space Mitochondrial matrix Q C NADH dehydrogenase cytochrome bc complex cytochrome c oxidase complex Inner mitochondrial membrane

9. AP Biology Electron Transport Chain intermembrane space mitochondrial matrix inner mitochondrial membrane NAD + Q C NADH H 2 O H+H+ e–e– 2H + +O2O2 H+H+ H+H+ e–e– FADH 2 1212 NADH dehydrogenase cytochrome bc complex cytochrome c oxidase complex FAD e–e– H H  e- + H + NADH  NAD + + H H p e Building proton gradient! What powers the proton (H + ) pumps?…

10. AP Biology H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ ATP NAD + Q C NADH H 2 O H+H+ e–e– 2H + +O2O2 H+H+ H+H+ e–e– FADH 2 1212 NADH dehydrogenase cytochrome bc complex cytochrome c oxidase complex FAD e–e– Stripping H from Electron Carriers  Electron carriers pass electrons & H + to ETC  H from NADH & FADH 2  electrons are stripped from H atoms  H + (protons)  electrons passed from one electron carrier to next (ETC)  flowing electrons = energy to do work  (Work) - transport proteins pump H + (protons) across inner membrane to intermembrane space ADP + P i TA-DA!! Moving electrons do the work! H+H+ H+H+ H+H+

11. AP Biology But what “pulls” the electrons down the ETC? electrons flow downhill to O 2 oxidative phosphorylation O2O2

12. AP Biology Electrons flow downhill  Electrons move in steps from carrier to carrier downhill to oxygen  each carrier more electronegative  controlled oxidation  controlled release of energy make ATP instead of fire!

13. AP Biology H+H+ ADP + P i H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ We did it! ATP  Set up a H + gradient  Allow the protons to flow through ATP synthase  Synthesizes ATP ADP + P i  ATP Are we there yet? “proton-motive” force

14. AP Biology  The diffusion of ions across a membrane  build up of proton gradient so H+ could flow through ATP synthase to build ATP Chemiosmosis Chemiosmosis links the Electron Transport Chain to ATP synthesis So that’s the point!

15. AP Biology Electron Transport Chain  http://vcell.ndsu.edu/animations/etc/mo vie-flash.htm http://vcell.ndsu.edu/animations/etc/mo vie-flash.htm

16. AP Biology Peter Mitchell  Proposed chemiosmotic hypothesis  revolutionary idea at the time 1961 | 1978 1920-1992 proton motive force

17. AP Biology H+H+ H+H+ O2O2 + Q C ATP Pyruvate from cytoplasm Electron transport system ATP synthase H2OH2O CO 2 Krebs cycle Intermembrane space Inner mitochondrial membrane 1. Electrons are harvested and carried to the transport system. 2. Electrons provide energy to pump protons across the membrane. 3. Oxygen joins with protons to form water. 2H + NADH Acetyl-CoA FADH 2 ATP 4. Protons diffuse back in down their concentration gradient, driving the synthesis of ATP. Mitochondrial matrix 2 1 H+H+ H+H+ O2O2 H+H+ e-e- e-e- e-e- e-e- ATP

18. AP Biology Cellular respiration 2 ATP ~34 ATP ++ ~40 ATP

19. AP Biology Summary of cellular respiration  Where did the glucose come from?  Where did the O 2 come from? (Molecular oxygen)  Where did the CO 2 come from?  Where did the CO 2 go?  Where did the H 2 O come from?  Where did the ATP come from?  What else is produced that is not listed in this equation?  Why do we breathe?  Why do we eat? C 6 H 12 O 6 6O 2 6CO 2 6H 2 O ~36-38 ATP  +++

20. AP Biology  ETC backs up  nothing to pull electrons down chain  NADH & FADH 2 can’t unload H  ATP production ceases  cells run out of energy  and you die! Taking it beyond…  What is the final electron acceptor in Electron Transport Chain? O2O2  So what happens if O 2 unavailable? NAD + Q C NADH H 2 O H+H+ e–e– 2H + +O2O2 H+H+ H+H+ e–e– FADH 2 1212 NADH dehydrogenase cytochrome bc complex cytochrome c oxidase complex FAD e–e–

21. AP Biology 2006-2007 What’s the point? The point is to make ATP ! ATP

22. AP Biology What about fats?  Only sugars undergo Glycolysis  Fats are digested to fatty acids and glycerol  Each fatty acid is oxidized to Acetyl CoA’s Ex. C 17 H 35 COOH becomes 9 Acetyl CoA’s because it has 18 C’s and each Acetyl CoA has 2 C’s  The Acetyl CoA’s enter the Kreb Cycle and produce about 15 ATP each

23. AP Biology Summary animation  https://www.youtube.com/watch?v=Fcu _8URp4Ac https://www.youtube.com/watch?v=Fcu _8URp4Ac  http://www.sumanasinc.com/webconten t/animations/content/cellularrespiration. html http://www.sumanasinc.com/webconten t/animations/content/cellularrespiration. html  http://sepuplhs.org/high/sgi/teachers/p hotosynthesis2_sim.html http://sepuplhs.org/high/sgi/teachers/p hotosynthesis2_sim.html