Biochemistry II Test 2

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Biochemistry II Test 2
2015-03-17 10:13:49
Biochemistry Test 2
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  1. glycogen is...
    a polymer of glucose residues linked by alpha 1-4 and alpha 1-6 linkages
  2. Glycogenolysis
    The breakdown of glycogen
  3. Glycogen Phosphorylase
    releases a G1P if it is at least 5 units away from a branch point
  4. Glycogen Debranching Enzyme
    removes branches making more residues available to glycogen phosphorylase, transders alpha 1-4 trisaccharides from a limit brancce to the non reducing end of another branch and hydrolyzes the alpha 1-6 glycosidic linkage
  5. Phosphoglucomutase
    G1P to G6P
  6. Liver
    Regulates a constant supply of glucose
  7. How is glucose generated in the liver
    G6P to glucose by G6Pase
  8. what do muscles and other tissues not have that causes them to retain glucose
  9. Where is G6Pase located and how does G6P get there?
    G6Pase is in the ER and G6P gets there through a translocator
  10. How does glucose leave the liver
  11. What is McArdel's Disease
    McArdel's Disease is when individuals lack muscle glycogen phosphorylase but their muscles still contain high levels of glycogen
  12. UDP-glucose phosphorylase
    combines G1P with UTP to produce UDP-glucose
  13. Glycogen synthase
    transfers a glucose unit from UDP-glucose to the non-reducing end forming an alpha 1-4 glycosidic linkage. This enzyme can only extend already existing chains
  14. How is UTP replenished
    Nucleoside Phosphate Kinase
  15. Glycogen Branching Enzyme
    amylo-1,4-1,6-transglycosylase, creates branches by taking a 7-residue segment from the end of a chain to a C6OH and this segment must come from a chain that is at least 11 units long so that the new branch can be 4 residues away from the last one
  16. What is chain formation initiated by?
  17. Glycogen Phosphorylase requires ________
    pyridoxal-5'-phosphate which has R (active) and T (inactive) conformations
  18. What inhibits Glycogen phosphorylase
    high ATP, G6P, and glucose
  19. What activates glycogen phosphorylase?
    high AMP
  20. What are the two forms of glycogen phosphorylase?
    • phosphorylated form, a, is more active
    • unphosphorylated form, b, is less active
  21. What is glycogen synthase inhibited by?
  22. What is glycogen synthase activated by?
    ATP and G6P
  23. What are the two forms of glycogen synthase?
    • phosphorylated, b, less active
    • unphosphorylated, a, more active
  24. What role does Protein Kinase A play in glycogen synthesis
    Protein Kinase A activates glycogen phosphorylase a which with calcium inactivates glycogen synthase
  25. What activates Protein Kinase A
  26. What is the role of phosphoprotein phosphotase -1
    PP1 leads to increased synthesis by decreasing phosphorylation
  27. What inhibits PP1
    • PP1 is inhibited by PKA and thus glycogen breakdown occurs
    • In the liver it is inhibited by the binding of glycogen phosphorylase
  28. What effects to insulin and epinephrine have on Glycogen Synthesis
    they increase glucose transport and decrease cAMP thus increasing protein synthesis
  29. Pyruvate Carboxylase
    Pyruvate to oxaloacetate
  30. PEPCK
    oxaloacetate to phosphoenolpyruvate
  31. Where is oxaloacetate generated
  32. If PEPCK is cytosolic...
    PEP is transported out as malate or aspartate which generates NADH
  33. If PEPCK is mitochondrial...
    PEP just moves out
  34. What are the net energy costs of Pyruvate to Phosphoenol pyruvate through the gluconeogenesis pathway?
    4 ATP
  35. O-linked glycosylation
    glycosylation of an OH at serine, threonine, or tyrosine
  36. N-linked glycosylation
    • glycosylation at an N of asparagine or argenine
    • this requires dolichol phosphate
  37. Pyruvate to Acetyl-CoA
    Pyruvate DH
  38. Pyruvate DH
    made up of pyruvate DH, dihydrolipoyl transacetylase, dihydrolipoyl DH
  39. Multienzyme complexes
    • minimize the diffusion distance enhancing the reaction rate
    • channel intermediates to minimize side reactions
  40. Pyruvate DH (E1)
    • requires TPP
    • decarboxylates pyruvate with the formation of hydroxyethyl-TPP intermediate
  41. Dihydrolipoyl transacetylase (E2)
    • contains a lipoamide group that is attacked by hydroxyethyl eliminating TPP
    • catalyzes a reaction where an acetyl group is transferred to a CoA yielding Acetyl-CoA and dihydrolipoamide-E2
  42. Dihydrolipoyl DH
    reoxidizes dihydrolipoamide and contains a cys-cys and FAD
  43. What oxidizes dihydrolipoyl DH?
    a mechanism in which FAD funnels electrons to NAD+
  44. What is the Citric Acid Cycle
    • 8 reactions that oxidize acetyl group to CO2, yields 2 CO2, 3 NADH, 1 FADH, and 1 GTP
    • regenerates oxaloacetate in the last step
  45. Glyoxylate Cycle
    acetyl-CoA to oxaloacetate
  46. where does glyoxylate occur?
    mitochondria and glyoxysome
  47. Electron Transport Chain
    • consumes oxygen and generates carbon dioxide
    • oxygen is reduced and the carbon atoms of glucose are oxidized
    • overall, 12 electron pairs are reduced (10 NADH and 2 FADH2)
  48. Malate-Aspartate Shuttle
    oxaloacetate is reduced to malate to be transferred into the mitochondria
  49. Glycerophosphate shuttle
    NADH to NAD+ (3-phosphoglycerol) and FADH2
  50. ADP/ATP Translocator
    one ADP is imported for every ATP exported
  51. How does Pi enter the mitochondira
    through a phosphate carrier
  52. Redox centers have progressively _______ affinities and the reduction potentials go from ____ to ______
    greater; lower; higher
  53. Complex I
    • NADH to NAD+ and reduction of CoQ
    • NADH-coenzymeQ oxidoreductase 
    • occurs stepwise 
    • FMN and CoQ link NADH (2) and cytochromes (1)
    • 4 protons are translocated
  54. Complex II
    • FADH2 to FAD and reduction of CoQ
    • succinate-coenzyme Q oxidoreductase
  55. Complex III
    • oxidizes CoQ and reduces 2 cytochrome c molecules
    • inhibited by antimycin A
    • CoQ-cytochrome c reductase (cytochrome bc1)
    • 4 protons are translocated
  56. Q cycle
    • 2 cycle reoxidation
    • for every 2 CoQH2 that enter one is regenerated
  57. Complex IV
    • reoxidation of 4 cytochrome c molecules and reduction of O2 to H2O
    • Inhibited by cyanide
    • Cytochrome C Oxidase
    • uses electrons from 2 Q cycles 
    • 4 protons are taken up from the matrix and 4 are translocated into the intermembrane space
  58. Complex V
    ATP synthase
  59. Oxidative Phosphorylation
    at least 2 protons are required for ATP synthesis, F1F0 protein
  60. F1F0 Protein
    • F1 is the knob (ADP to ATP) and F0 is the proton channel
    • inhibited by IF1
  61. What activates cytochrome c oxidase?
    high concentration of reduced cytochrome c, high NADH, or low ATP
  62. Myocardial infarction and stroke
    • result from lack of oxygen to the brain and heart
    • ATP and phosphocreatine are used up first 
    • osmotic balance is interrupted and organelles begin to swell, pH is lower and enzymes begin degrading cellular contents, death and irreversible damage occurs
  63. Superoxide radicals
    • initiate chain reaction by stealing electrons
    • Lipids disrupt membranes, DNA causes point mutations, Amino acids modify enzyme functions
    • leads to parkinson's, alzheimers, huntingtons, and aging
  64. Antioxidants
    • destroy free radicals
    • SOD (super oxide - H2O2)
    • Catalase and Glutathione peroxidase degrade H2O2 to water
    • Vitamin C and Vitamin E