Cellular Respiration & Electron Transport Chain PDF

Cellular Respiration Stage 4: Electron Transport Chain AP Biology 2006-2007  Cellular respiration AP Biology  What’s the point? The point...

Cellular Respiration Stage 4: Electron Transport Chain AP Biology 2006-2007  Cellular respiration AP Biology  What’s the point? The point is to make ATP! ATP AP Biology 2006-2007  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! There’s got to be a better way! I need a lot more ATP! A working muscle recycles over AP Biology 10 million ATPs per second  There is a better way!  Electron Transport Chain  series of proteins 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 ~36 ATP from 1 glucose!  only in presence of O (aerobic respiration) 2 That sounds more O2 AP Biology like it!  Mitochondria  Double membrane  outer membrane  inner membrane  highly folded cristae  enzymes & transport proteins  intermembrane space  fluid-filled space between membranes Oooooh! Form fits AP Biology function!  Electron Transport Chain Inner mitochondrial Intermembrane space membrane C Q NADH cytochrome cytochrome c dehydrogenase bc complex oxidase complex Mitochondrial matrix AP Biology  Remember the Electron Carriers? glucose Krebs cycle Glycolysis G3P 2 NADH 8 NADH 2 FADH2 Time to break open the piggybank! AP Biology  Electron Transport Chain NADH NAD+ + H Building proton gradient! e intermembrane space p H+ H+ H+ inner mitochondrial H e- + H+ C membrane Q e– e – H e– FADH2 FAD H 1 NADH 2H+ + O2 H 2O NAD + 2 NADH cytochrome cytochrome c dehydrogenase bc complex oxidase complex mitochondrial matrix AP Biology What powers the proton (H+) pumps?…  Stripping H from Electron Carriers  Electron carriers pass electrons & H+ 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)  flowing electrons = energy to do work  transport proteins in membrane pump H+ (protons) across inner membrane to intermembrane space H+ H+ H+ H H H H + + + + TA-DA!! H + H + H+ H+ H+ H H+ + Moving electrons do the work! C Q e– e– e – FADH2 FAD ADP 1 NADH 2H+ + O2 H2O + Pi NAD+ 2 NADH cytochrome cytochrome c dehydrogenase bc complex oxidase complex ATP AP Biology H+ But what “pulls” the electrons down the ETC? H2O O2 electrons flow downhill AP Biology to O2 oxidative phosphorylation  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! AP Biology  “proton-motive” force We did it! H+ H+ H+ H+  Set up a H+ H+ H + H+ H+ gradient  Allow the protons to flow through ATP synthase  Synthesizes ATP ADP + Pi ADP + Pi ATP Are we ATP there yet? H+ AP Biology  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’s the point! AP Biology  1961 | 1978 Peter Mitchell  Proposed chemiosmotic hypothesis  revolutionary idea at the time proton motive force 1920-1992 AP Biology  Pyruvate from Intermembrane Inner H + cytoplasm space mitochondrial H + membrane Electron transport C system Q NADH e- 2. Electrons H+ provide energy 1. Electrons are harvested Acetyl-CoA and carried to the e- transport system. to pump protons across NADH e- the membrane. HO 2 Krebs e- 3. Oxygen joins 1 O FADH2 with protons to cycle 2 +2 O2 form water. 2H+ CO2 H+ ATP H+ ATP ATP 4. Protons diffuse back in down their concentration ATP Mitochondrial gradient, driving the synthase matrix synthesis of ATP. AP Biology  ~4 Cellular respiration 0A TP 2 ATP + 2 ATP + ~36 ATP AP Biology  Summary of cellular respiration C6H12O6 + 6O2 6CO2 + 6H2O + ~40 ATP  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? AP Biology  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 & FADH can’t unload H 2  ATP production ceases  cells run out of energy AP Biology  and you die!  What’s the point? The point is to make ATP! ATP AP Biology 2006-2007