MCAT BIC Ch 10

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DesLee26
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304581
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MCAT BIC Ch 10
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2015-06-29 17:11:34
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  1. Why is cyanide a poison?
    it binds irreversibly to cyt ala3, a protein in the ETC, thus inhibiting aerobic respiration from yielding the ATP the body requires to function properly

    it blocks oxygen from binding to the ETC--> tissue hypoxia
  2. CoA is a __, containing an __ group. When acetyl-CoA forms, it does so via __.
    • thiol
    • --SH
    • covalent attachment of the acetyl group to the --SH group
  3. Pyruvate dehydrogenase
    pyruvate is oxidized, yielding CO2, while the remaining two-carbon molecule binds covalently to TPP
  4. Dihydrolipoyl transacetylase
    two-carbon molecule bonded to TPP is oxidized and transferred to lipoic acid, whose disulfide group acts as an oxidizing agent, creating the acetyl group.

    It then catalyzes the CoA-SH interaction with the newly formed thioester link, causing transfer of an acetyl group to form acetyl-CoA; lipoic acid is left in its reduced form
  5. Dihidrolipoyl dehydrogenase
    FAD is used as a coenzyme in order to reoxidize lipoic acid, allowing lipoid acid to facilitate acetyl-CoA formation in future reactions. 


    • As lipoid acid is reoxidized, FAD is reduced to FADH2
    • In subsequent reactions, FADH2 is reoxidized to FAD, while NAD+ is reduced to NADH
  6. What other pathways are capable of producing fatty acids?
    beta (fatty acd) oxidation

    amino acid catabolism

    ketones

    alcohol
  7. beta oxidation
    because fatty acyl-CoA cannot cross the inner mitochondrial membrane, the fatty acyl group is transferred to carnitine via a transesterification reaction

    once acyl-CoA is in the matrix, beta oxidation occurs
  8. function of carnitine
    cary the acyl group from a cytosolic CoA-SH to a mitochondrial CoA-SH
  9. amino acid catabolism
    some amino acids form acetyl-CoA by losign their amino group via transamintation; their carbon skeletons form ketone bodies
  10. ketones
    ketones can poduce acetyl CoA
  11. alcohol
    alcohol dehydrogenase or acetaldehyde dehydrogenase
  12. In regards to the CAC, what happens if oxygen is absent?
    NADH and FADH2 will accumulate if oxygen is not available.
  13. What is isoctrate
    an isomer
  14. What converts citrate to isocitrate?
    aconitase
  15. What is the rate limiting step in the CAC?
    isocitratedehydrogenase
  16. synthetases
    reate new covalent bonds with energy input
  17. nucleosidediphosphate
    transfers a phosphate from GTP to ADP
  18. Only step of the CAC that doesn't occur in the matrix is...
    fumaate formation by succinate dehyrogenase, which occurs in the inner mitochondrial membrane
  19. net results and atp yield of the CAC
    Per cycle: 

    • 4 NADH--> 10 ATP
    • 1 FADH2--> 1.5 ATP
    • 1 GTP--> 1 ATP

    Total: 12.5 ATP per pyruvate= 25 ATP
  20. Yield for glycolysis
    two ATP and two NADH
  21. What inhibits acetyl CoA production?
    phsophorylating PDH
  22. What activates PDH?
    pyruvate dehydrogenase phosphatase in response to high levels of ADP
  23. control points of the CAC
    1) citrate synthase

    2) isocitrate dehydrogenase

    3) alpha-ketoglutarate dehydrogenase complex
  24. control of citrate synthase
    ATP and NADH function as allosteric inhibiton of citrate

    ADP and NAD+ fuction as allosteric activators
  25. control of alpha-ketoglutarate dehydrogenase complex
    succinyl-CoA and NADH are inhibitors; ATP is as well

    stimulated bby calcium and ADP
  26. During a metabolically active state, __ and __ should rise and __ and __ decline.
    ADP and NAD+

    ATP and NADH
  27. The formation of ATP is __ and electron transport is __.
    • endergonic
    • exergonic
  28. How many protons are pumped into the intermembrane space by...

    Complex I
    1) four
  29. How many protons are pumped into the intermembrane space by...

    Complex II
    zero
  30. Why are cytochrome c molecules needed?
    becase coenzyme Q only transfers one electron at a time via the Q cycle
  31. Explain the Q cycle.
    two electrons are shuttled from ubiquinol near the intermembrane space to a molecule of ubiquinone near the mitochondrial matrix. Another two electrons are attached to heme moieties, reducing two molecules to cyt c. A carrier assists.
  32. How many protons are pumped into the intermembrane space by...

    Complex III
    four protons
  33. How many protons are pumped into the intermembrane space by...

    Complex IV
    two
  34. ATP synthase parts
    F0: functions as an ion channel, so protons travel through F0 along their gradient back into the matrix

    F1: utilizes the energy released from the electrochemical gradient to phosphorylate ADP to ATP
  35. What does the theory of conformational coupling suggest?
    that the relationship between the proton gradient and ATP synthesis is indirect. Instead, ATP is released by the synthase as a result of conformational change caused by the gradient
  36. What happens if O2 is limited?
    the rate of oxidative phosphorylation decreases, and the concentrations of NADH and FADH2 increase. The accumulation of NADH inhibits the CAC
  37. In the presence of adequate O2, the rate of oxidative phosphorylation is dependent on __. The concentrations of ADP and ATP are __.
    the availability of ADP

    reciprocally related

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