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Electron Transport Chain

Electron Transport Chain . Introduction . NADH and FADH 2 are electron carriers Each H atom contains 1 electron These electrons are transferred to a series of components that are found in the inner mitochondrial membrane This is known as the Electron Transport Chain . 1. 1. 3. 2. 2.

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Electron Transport Chain

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  1. Electron Transport Chain

  2. Introduction • NADH and FADH2are electron carriers • Each H atom contains 1 electron • These electrons are transferred to a series of components that are found in the inner mitochondrial membrane • This is known as the Electron Transport Chain

  3. 1 1 3 2 2 6 0 0 0 2 0 1 • Therefore, before we enter the electron transport chain we have: • 10 NADH • 2 FADH2

  4. The ETC is a series of proteins arranged as a chain on the cristae of the inner mitochondrial membrane • The components of the ETC are arranged in order of increasing electronegativity: starts with the weakest attractor of electrons and ends with the strongest

  5. Complexes in the ETC • NADH dehydrogenase (Complex I ) • Ubiquinone (Co-enzyme Q) (Shuttle) • Cytochrome b-c (Complex II) • Cytochrome c (Shuttle) • Cytochrome oxidase (Complex III) Electrons get passed from complex to complex like a baton handed from runner to runner in a relay race

  6. NADH passes its electrons on to Complex I – NADH dehydrogenase • FADH2 passes its electrons to Q (shuttle)

  7. Proton Pumps • Move protons (H+ ions) from the mitochondrial matrix into the intermembrane space • Protons moving against the gradient (need energy to do this), the electrons moving through the complexes provide this energy • A proton gradient is created and the energy powers the ATP synthase enzyme- an ATP pump called an ATPase • 3 proton pumps • Complex I • Complex II • Complex III

  8. NADH passes its electrons on to Complex I – NADH dehydrogenase • FADH2 passes its electrons to Q (shuttle) How many protons get pumped for every NADH? 3 How many protons get pumped for every FADH2? 2

  9. Final Electron Acceptor • Why do we need oxygen for cellular respiration? • Oxygen has a strong attraction for electrons • It takes the two electrons from the final proton complex (III) (cyctochrome oxidase) and takes two protons from the matrix and forms water 2e- + 2H++ O2 H2O

  10. Chemiosmosis • Protons accumulate in the intermembrane space of the mitochondria  this creates an electrochemical gradient • The protons want to move back in to mitochondrial matrix Intermembrane Space H+ (proton) Mitochondrial Matrix

  11. ATP Synthase • The protons cannot move through the phospholipid bilayer • Therefore, they are forced to move through special proton channels associated with the enzyme ATP synthase (ATPase) • Protons move through the ATPase complex and as a result the synthesis of ATP from ADP and P occur in the matrix

  12. How many ATP are formed? • Start off with 10 NADH: • Each NADH pumps out 3 H+ • Each H+ makes one ATP molecule • 10 x 3 = 30 ATP are generated from NADH • Start off with 2 FADH2 • Each FADH2 pumps out 2 H+ • 2 x 2 = 4 ATP are generated from FADH2 Therefore a total of 34 ATP are generated by the electron transport chain.

  13. Putting it all together… The Electron Transport Chain: • creates a proton gradient through transporting electrons • creates water • creates ATP • regenerates electron carriers (NAD+ and FAD)

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