1 / 20

Cellular Respiration Stage 4: Electron Transport Chain

Cellular Respiration Stage 4: Electron Transport Chain. Cellular respiration. What’s the point?. The point is to make ATP !. ATP. ATP accounting so far…. Glycolysis  2 ATP Kreb’s cycle  2 ATP Life takes a lot of energy to run, need to extract more energy than 4 ATP !.

lalasa
Download Presentation

Cellular Respiration Stage 4: Electron Transport Chain

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Cellular RespirationStage 4: Electron Transport Chain

  2. Cellular respiration

  3. What’s thepoint? The pointis to makeATP! ATP

  4. ATP accounting so far… • Glycolysis 2ATP • Kreb’s cycle 2ATP • Life takes a lot of energy to run, need to extract more energy than 4 ATP! There’s got to be a better way! What’s the point? A working muscle recycles over 10 million ATPs per second

  5. O2 There is a better way! • Electron Transport Chain • series of molecules built into inner mitochondrial membrane • along cristae • transport proteins& enzymes • transport of electrons down ETC linked to pumping of H+ to create H+ gradient • yields ~34 ATP from 1 glucose! • only in presence of O2 (aerobic respiration) Thatsounds morelike it!

  6. Mitochondria • Double membrane • outer membrane • inner membrane • highly folded cristae • enzymes & transport proteins • intermembrane space • fluid-filled space between membranes Oooooh!Form fits function!

  7. Innermitochondrialmembrane Electron Transport Chain Intermembrane space C Q cytochromebc complex cytochrome coxidase complex NADH dehydrogenase Mitochondrial matrix

  8. Remember the Electron Carriers? glucose Krebs cycle Glycolysis G3P 8 NADH 2 FADH2 4 NADH Time tobreak openthe bank!

  9. e p 1 2 Electron Transport Chain Building proton gradient! NADH  NAD+ + H intermembranespace H+ H+ H+ innermitochondrialmembrane H  e- + H+ C e– Q e– H e– FADH2 FAD H NADH 2H+ + O2 H2O NAD+ cytochromebc complex cytochrome coxidase complex NADH dehydrogenase mitochondrialmatrix What powers the proton (H+) pumps?…

  10. H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ C e– Q e– 1 2 e– FADH2 FAD NADH 2H+ + O2 H2O NAD+ cytochromebc complex NADH dehydrogenase cytochrome coxidase complex Stripping H from Electron Carriers • NADH passes electrons to ETC • H cleaved off NADH & FADH2 • electrons stripped from H atoms  H+ (protons) • electrons passed from one electron carrier to next in mitochondrial membrane (ETC) • transport proteins in membrane pump H+ (protons) across inner membrane to intermembrane space TA-DA!! Moving electronsdo the work! ADP+ Pi ATP

  11. O2 But what “pulls” the electrons down the ETC? electronsflow downhill to O2 oxidative phosphorylation

  12. Electrons flow downhill • Electrons move in steps from carrier to carrier downhill to O2 • each carrier more electronegative • controlled oxidation • controlled release of energy make ATPinstead offire!

  13. H+ H+ H+ H+ H+ H+ H+ H+ ADP + Pi H+ “proton-motive” force We did it! • Set up a H+ gradient • Allow the protonsto flow through ATP synthase • Synthesizes ATP ADP + PiATP ATP Are wethere yet?

  14. Chemiosmosis • The diffusion of ions across a membrane • build up of proton gradient just so H+ could flow through ATP synthase enzyme to build ATP Chemiosmosis links the Electron Transport Chain to ATP synthesis So that’sthe point!

  15. 1961 | 1978 Peter Mitchell • Proposed chemiosmotic hypothesis • revolutionary idea at the time proton motive force 1920-1992

  16. Intermembrane space Pyruvate from cytoplasm Inner mitochondrial membrane H+ H+ Electron transport system C Q NADH e- H+ 2. Electrons provide energy to pump protons across the membrane. 1. Electrons are harvested and carried to the transport system. e- Acetyl-CoA NADH e- H2O e- Krebs cycle 3. Oxygen joins with protons to form water. 1 FADH2 O2 2 O2 + 2H+ H+ CO2 H+ 2 ATP ATP 32 4. Protons diffuse back in down their concentration gradient, driving the synthesis of ATP. ATP synthase Mitochondrial matrix

  17. ~40 ATP Cellular respiration + + + 2 ATP ~2 ATP 2 ATP ~34 ATP

  18. C6H12O6 + 6CO2 + 6H2O + ~40 ATP 6O2 Summary of cellular respiration • Where did the glucose come from? • Where did the O2 come from? • Where did the CO2 come from? • Where did the CO2 go? • Where did the H2O come from? • Where did the ATP come from? • What else is produced that is not listed in this equation? • Why do we breathe?

  19. H+ H+ H+ C e– Q e– 1 2 e– FADH2 FAD NADH 2H+ + O2 H2O NAD+ cytochromebc complex NADH dehydrogenase cytochrome coxidase complex Taking it beyond… • What is the final electron acceptor in Electron Transport Chain? O2 • So what happens if O2 unavailable? • ETC backs up • nothing to pull electrons down chain • NADH & FADH2 can’t unload H • ATP production ceases • cells run out of energy • and you die!

  20. What’s thepoint? The pointis to makeATP! ATP

More Related