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Cellular Respiration Stage 4: Electron Transport Chain

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Cellular Respiration Stage 4: Electron Transport Chain

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    1. 2006-2007 Cellular Respiration Stage 4: Electron Transport Chain

    2. Cellular respiration

    3. 2006-2007

    4. 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!

    5. 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)

    6. Mitochondria Double membrane outer membrane inner membrane highly folded cristae enzymes & transport proteins intermembrane space fluid-filled space between membranes

    7. Electron Transport Chain

    8. Remember the Electron Carriers?

    9. Electron Transport Chain

    10. 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 Oxidation refers to the loss of electrons to any electron acceptor, not just to oxygen. Uses exergonic flow of electrons through ETC to pump H+ across membrane.Oxidation refers to the loss of electrons to any electron acceptor, not just to oxygen. Uses exergonic flow of electrons through ETC to pump H+ across membrane.

    11. Pumping H+ across membrane … what is energy to fuel that? Can’t be ATP! that would cost you what you want to make! Its like cutting off your leg to buy a new pair of shoes. :-( Flow of electrons powers pumping of H+ O2 is 2 oxygen atoms both looking for electronsPumping H+ across membrane … what is energy to fuel that? Can’t be ATP!that would cost you what you want to make! Its like cutting off your leg to buy a new pair of shoes. :-( Flow of electrons powers pumping of H+ O2 is 2 oxygen atoms both looking for electrons

    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 Electrons move from molecule to molecule until they combine with O & H ions to form H2O It’s like pumping water behind a dam -- if released, it can do work Electrons move from molecule to molecule until they combine with O & H ions to form H2O It’s like pumping water behind a dam -- if released, it can do work

    13. We did it! Set up a H+ gradient Allow the protons to flow through ATP synthase Synthesizes ATP ADP + Pi ? ATP

    14. 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 Chemiosmosis is the diffusion of ions across a membrane. More specifically, it relates to the generation of ATP by the movement of hydrogen ions across a membrane. Hydrogen ions (protons) will diffuse from an area of high proton concentration to an area of lower proton concentration. Peter Mitchell proposed that an electrochemical concentration gradient of protons across a membrane could be harnessed to make ATP. He likened this process to osmosis, the diffusion of water across a membrane, which is why it is called chemiosmosis.Chemiosmosis is the diffusion of ions across a membrane. More specifically, it relates to the generation of ATP by the movement of hydrogen ions across a membrane. Hydrogen ions (protons) will diffuse from an area of high proton concentration to an area of lower proton concentration. Peter Mitchell proposed that an electrochemical concentration gradient of protons across a membrane could be harnessed to make ATP. He likened this process to osmosis, the diffusion of water across a membrane, which is why it is called chemiosmosis.

    15. Peter Mitchell Proposed chemiosmotic hypothesis revolutionary idea at the time

    17. Cellular respiration

    18. 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? Where did the glucose come from? from food eaten Where did the O2 come from? breathed in Where did the CO2 come from? oxidized carbons cleaved off of the sugars Where did the CO2 go? exhaled Where did the H2O come from? from O2 after it accepts electrons in ETC Where did the ATP come from? mostly from ETC What else is produced that is not listed in this equation? NAD, FAD, heat!Where did the glucose come from? from food eaten Where did the O2 come from? breathed in Where did the CO2 come from? oxidized carbons cleaved off of the sugars Where did the CO2 go? exhaled Where did the H2O come from? from O2 after it accepts electrons in ETC Where did the ATP come from? mostly from ETC What else is produced that is not listed in this equation? NAD, FAD, heat!

    19. Taking it beyond… What is the final electron acceptor in Electron Transport Chain? What if you have a chemical that punches holes in the inner mitochondrial membrane?What if you have a chemical that punches holes in the inner mitochondrial membrane?

    20. 2006-2007

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