10-26-09_mitochondria_ATPsynthaseB

10-26-09_mitochondria_ATPsynthaseB - While all other...

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While all other sciences have advanced, that of government is at a standstill - little better understood, little better practiced now than three or four thousand years ago. John Adams I was bold in the pursuit of knowledge, never fearing to follow truth and reason to whatever results they led, and bearding every authority which stood in their way. Thomas Jefferson
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Announcements .Quiz 6 is due next Monday at noon. It will be available by the end of today. A second research article summary will be due on November 9 instead of the cell simulation project listed in the syllabus. Please choose a different paper from the list in Blackboard.
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Take a ride down the electron transport chain! Takes place in inner mitochondrial membrane Sequentially uses free energy of electron transfer to drive H+ out into intermembrane space Each of large ΔE'0 steps indicated by arrow and correspond to H+ movement that will ultimately lead to formation of 1 ATP FADH2 starts at later step and has lower total ΔE'0 , so only 2 ATP formed
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Initial electron transfer from NADH to NADH dehyrogenase (complex I) Complex I is huge, L shaped complex formed from 45 subunits and weighing 1 million Daltons NADH transfers electrons to flavoprotein (FMN) and reduces it From Fe-S to bound ubiquinone, which diffuses to complex III 4 H+ move into intermembrane space for each 2 e-
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Succinate to fumarate in the TCA cycle produces FADH2 by succinate dehydrogenase (complex II) First, FADH2 is formed Travels 40 angstroms through 3 Fe-S clusters to bound ubiquinone Ubiquinone is released and can go to complex III No H+ moved across membrane
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Reduced ubiquinone from complexes I and II diffuse through membrane to complex III Complex III, aka cytochrome bc1 Reduced ubiquinone called ubiquinol Ubiquinol transfers electrons to cytochrome b1 and iron- sulfur transfer regions to cytochrome c1 For every pair of electrons, 4 H+ moved to intermembrane space
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Transfer of protons by ubiquinol Protons released into intermembrane space in 2 separate steps 2 H+ (protons) derived from the UQH2 that entered the complex; 2 more protons translocated across membrane as part of a second UQH2 molecule cytochrome c is a peripheral membrane shuttle protein between complexes III & IV
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From cytochrome c, we reach complex IV (cytochrome oxidase), where O2 finally accepts the electrons and then is converted H2O 2 cyt c 2+ + 2 H + + 1/2 O2 —> 2 cyt c 3+
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10-26-09_mitochondria_ATPsynthaseB - While all other...

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