Oxidative Phosphorylation

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Oxidative Phosphorylation
2015-11-25 13:15:22
oxidative phosphorylation

Oxidative Phosphorylation
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  1. NADH and FADH come from the degredation of what substances
    • Glucose
    • Fatty acids
    • Amino Acids
  2. Conversion of electron to proton motive force is carried out by what 3 electron pumps
    • NADH-Q oxidoreductase
    • Q-cytochrome c oxidoreductase
    • Cytochrome c oxidase
  3. The electron driven pumps in oxidative phosphorylation contain what oxidation reduction centers
    • Quinones
    • Flavins
    • Iron sulfur clusters
    • hemes
    • copper ions
  4. Oxygen is the ultimate acceptor of NADH and FADH2 forming what
  5. Electron carries can be either bound to proteins or
    Diffuse freely in the membrane (most are soluble)
  6. Electron transport chains cannot
    Exist free in solution, but must be bound to a membrane to exchange electrons
  7. The further electrons go down to succeeding reactions
    The more exergonic they become
  8. The site of oxidative phosphorylation is where
    In the inner membrane of the mitochondria
  9. NAD+ and NADH funnels 2e- into
    Complex 1
  10. The NADH from glycolysis must do what to be incorporated into the electron transport chain
    They must be transported from the outside of the mitochondrial membrane to the inside to reach Complex 1
  11. FMN/FMNH2 accepts and transfers electrons how
    Singly or in pairs, and donates e- to CoQ
  12. FAD/FADH2 is a cofactor in what complex and funnels e- from where
    Complex 2, funnels electrons from mitochondria succinate onto CoQ
  13. A pair of e- in FADH2 results in what in comparison to NADH
    • FADH2 - 2 ATP
    • NADH - 3 ATP
  14. Fe-S has what function in Oxidative Phosphorylation
    Centers as a electron carrier, and is always complexed with proteins
  15. What are the diffusible e- carriers
    • Coenzyme Q (isoprenoid)
    • Cytochrome c (small protein)
  16. Coenzyme Q has what function
    Can carry 1e- or 2e- into the respiratory chain Funnels e- into cytochromes towards oxygen
  17. What can coenzyme Q draw electrons from
    • NADH
    • Succinate
    • FADH
    • Other flavin enzymes
  18. What is the job of cytochrome c
    Transfers e- between complexes 3 and 4 and cannot bind oxygen
  19. Which complexes are proton pumps
    1, 3, 4
  20. What happens in complex 1
    • It contains e- carriers FMN and FE-S
    • Passes e- from NADH to CoQ
    • Is a proton pump
  21. What is the job of complex 2
    • Contains FAD and FE-S e- carriers
    • Passes e- from succinate (TCA cycle) onto CoQ
    • Not a proton pump
  22. What is the job of complex 3
    • Contains Cyt b, FE-S, and cyt-c e- carriers
    • Passes e- from CoQ to Cyt-c
    • Is a proton pump
  23. What is the job of complex 4
    • Contains electron carriers Cyt-a
    • Passes e- from Cyt-c to Oxygen
    • Is a proton pump
    • Copper containing
  24. What is complex 5
    The ATP synthase which uses the proton gradient
  25. How does a proton pump work
    It is an integral protein in the mitochondrial inner membrane that physically moves protons from the matrix to the intermembrane creating an electrochemical potential which powers the ATP synthase
  26. The larger the reduction potential (E) the more
    Negative Delta G and thus the more likely to transfer
  27. What is the order of the least strongest to the strongest oxidant on the transport chain
    • NAD+
    • FMN
    • FAD
    • CoQ
    • Cyt b2 (Fe+3)
    • O2
  28. What happens to the value of the reduction potential (E) as the electron transport chain moves along
    It get larger, thus Delta G gets smaller
  29. The glycerol phosphate shuttle (FADH2-FAD) is particularly active where
    In the brain and produces 2 ATP
  30. The malate aspartate shuttle is particularly active where
    In the liver and heart and produces 3 ATP
  31. ATP is coupled to ADP entry into the mitochondria by
    ATP-ADP translocase driven by membrane potential
  32. What are the substrates to oxidative phosphorylation, and what else to they
    • ADP
    • Pi
    • O2
    • NADH
    • FADH2
    • They are rate limiting as well
  33. What is the chemiosmotic theory
    Electron transport creates an electron gradient outside the mitochondria (high e-) used for the ATP synthesis (proton motive force)
  34. What are the two units of the ATP synthase and their jobs
    • F1 Contains the catalytic site for ATP synthesis (in matrix)
    • F0 serves as a transmembrane channel (base) for H+ flow
  35. Rotenone
    • Blocks electron flow from NADH to CoQ (not absorbed by humans well)
    • Complex 1 inhibitor
  36. Amytal and other barbituates (Demerol) have what effect on Ox Phos
    Complex 1 inhibitor
  37. Antimycin effects ox phos how
    Blocks complex 3 (cytb -cytc1)
  38. Cyanide, azide, CO, and hydrogen sulfide have what effect on ox phos
    Block complex 4
  39. Oligomyocin (antibiotic) has what effect on the ATP synthase
    Inhibits F0
  40. 2,4 dinitrophenol and Pentachlorophenol have what effect on ox phos
    • They are uncoupling agents for e- carriers
    • These do not interfere with electron transport and in fact stimulate it by providing an alternative pathway to disapate energy of electron transport
  41. How is energy conserved with an uncoupler like dinitrophenol
    • Protons are driven out through the inner membrane like normal, however, they leak back in so rapidly that ATP synthesis does not occur.
    • Instead, the energy conserved is dissipated as heat
  42. What is an endogenous uncoupler
    Thermogenin (brown adipose tissue) keeps babies and hibernating animals warm by bypassing ATP synthesis and enhancing Complex's 1-4
  43. What are some endogenous sources for reactive oxygen species (ROS)
    • Electron transport chains
    • Mitochondria
    • Phagocytes
    • Flavins
    • Oxidases
  44. Where is over 90% of the oxygen consumed in cells
    Os Phos complex 4
  45. Oxygenases
    Enzymes that use oxygen to form oxidized products
  46. Oxidase
    An enzyme that promotes the transfer of a H from a substrate to an Oxygen making water or hydrogen peroxide
  47. What are some exogenous sources of ROS
    • Ionizing radiation
    • Light (visable/UV)
    • Redox cycling xenobiotics
  48. What are some antioxidant enzymes
    • Superoxide dismutase
    • Catalase (Haem)
    • Glutathione Peroxidase (Selenium)
  49. What are some low molecular weight antioxidants
    • Vit C (ascorbic acid)
    • Urate
    • Albumin
    • Vit E
    • Beta carotene
  50. Tocopherols/Tocotrienols
    Technical name of Vit E
  51. Peroxidase
    Enzyme that catalyzes the oxidation of a substance by hydrogen peroxide
  52. Lebers hereditary optic neuropathy (LHON)
    • Caused by a mutation in the mitochondrial DNA affecting the nervous system including the optic nerves
    • Single base change for complex 1 making a defective e- transfer from NADH to ubiquinone