Biochem Exam 2

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pharmd14
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38059
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Biochem Exam 2
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2010-09-29 16:03:28
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Biochemistry
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Lectures 8-12
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  1. What does the term Carbohydrate mean?
    polyhydroxy aldehydes and ketones
  2. Monosaccharide name for an aldehyde
    Aldose
  3. Monosaccharide term for Ketones
    Ketose
  4. 3 carbons in a monosaccaride
    triose
  5. 4 carbons in a monosaccharide
    tetrose
  6. 5 carbons in a monosaccharide
    pentose
  7. 6 carbons in a monosaccharide
    hexose
  8. Dihydroxyacetone
    only ketotriose
  9. Glyceraldehyde
    only Aldotiose

    *has a chiral carbon
  10. In a Fischer projection where is the most oxidized carbon?
    The top
  11. Groups that aren't part of the main chain are pointed which way?
    They project horizontally towards the viewer
  12. If the sterocenter at the bottom of the chain has an OH to the right, is the sugar D or L
    D
  13. If the sterocenter at the bottom the chain has an OH to the left is the sugar D or L?
    L
  14. Are the most common sugars in D or L form?
    D
  15. Enantiomers
    There is a change at every chiral carbon
  16. Epimers (special Diasteriomers)
    If theres a change at 1 chiral carbom
  17. Diasteriomers
    There is a change at more then 1 chiral carbon
  18. The most simple sugars of four or more carbons exist in what form?
    cyclic (hemiacetal/hemiketal) form
  19. What group in the sugar reacts with the carbonyl carbon?
    A hydroxy group
  20. For D sugars if the OH on the anomeric carbon is "up" then the carbon is what?
    Beta carbon
  21. For D sugars if the OH on the anomeric carbon is "down" then the carbon is what?
    Alpha carbon
  22. a 6-membered ring is called?
    Pyranose

    (most stable)
  23. A 5-membered ring is called?
    Furanose
  24. To form a cyclic sugar the attack of an alcohol on the carbonyl carbon forms what?
    Glucose
  25. What is formed at the anomeric carbon during the formation of cyclic sugars?
    Hemiacetal
  26. In the formation of the hemiacetal, an alpha anomeric carbon has the OH pointing?
    Down
  27. In the formation of the hemiacetal, a beta anomeric carbon has the OH pointing?
    Up
  28. What is a reducing sugar?
    a free aldehyde that can be oxidized
  29. In what function are reducing sugars important?
    They are important in the metabolism of polysaccarides
  30. The OH groups of sugars can reach with a phosphorylating agent to give what?
    Phosphate ester
  31. Phosphoesters are common in what kind of pathways?
    In metabolic pathways
  32. GlcNAc
    N-Acetylglucosamine
  33. What can the anomeric carbon react with?
    an OH group or an alchohol
  34. when the anomeric carbon reacts with an alchohol on another sugar what does it yeild?
    a glucosidic bond
  35. Animals lack what when it comes to cellulose?
    The enzymes necessary to hydrolyze cellulose
  36. what are starches
    starches are storage forms of glucose found in plants
  37. how do animals store glucose?
    as glycogen
  38. Where is the division between the 2 stages of glycolysis?
    Right after the second ATP is invested
  39. What is a kinase?
    It does phosphorylation with ATP, either using it or producing it.
  40. Step 1 of Glycolysis
    • 1. Hydroxy group attacks the phosphoanhydride on ATP
    • 2. Gives Glucose a charge
    • 3. Makes the Oxygen on C6 of Glucose more reactive
  41. Why is glucose given a charge in step 1 of glycolysis
    to keep it in the cell.
  42. What type of intermediate does step 2 of glycolysis go through?
    It goes through an enodiol intermediate to isomerize from an aldehyde to a ketone
  43. Why isn't C1 available for phosphorylation on glucose in glycolysis?
    It is anomeric, but C1 on Fru can be phosphorylated
  44. Step 1 of Glycolysis
    Glucose -> Glucose-6-Phosphate
  45. Step 2 of Glycolysis
    Glucose-6-Phosphate -> Fructose-6-Phosphate
  46. Step 3 of Glycolysis
    Fructose-6-Phosphate -> Fructose-1.6-biPhosphate
  47. Step 4 of Glycolysis
    Fructose-1,6-biPhosphate -> Trioses
  48. Step 5 of Glycolysis
    Isomerization of DHAP
  49. What does bis-phosphate mean?
    2 separate phosphates
  50. Allosteric regulation is based on what?
    Cell condition
  51. the reverse reaction of step 4 of glycolysis is what?
    an aldol condensation reaction
  52. Having 2 phosphose on a 6-carbon sugar allows what?
    Cleavage into 2 phosphorylated trioses
  53. DHAP and Glyc-3-P are in equilibrium that favors which one?
    DHAP
  54. Even though DHAP is favored over Glyc-3-P, it is rapidly converted. Why?
    Le'Chatlier's Principle
  55. The loop in Triose Phosphate Isomerase serves as what?
    A lid to prevent biologically useless but energtically favorable side reaction.
  56. overall glycolysis yields what?
    • 2 NADH
    • 2 ATP

    per glucose molecule
  57. Step 6 of Glycolysis
    Glyceraldehyde-3-Phosphate -> 1,3- Bis phosphoglycerate
  58. What does step 6 of Glycolysis produce?
    A high energy mixed anhydride bond
  59. In step 6 of glycolysis what preserves energy from the first step to couple it to the second step?
    The thiosester intermediated with the enzyme's cys residue
  60. Step 7 of Glycolysis
    1,3-Bisphosphoglycerate -> 3-phosphoglycerate
  61. What does step 7 of glycolysis produce?
    the first production of ATP from the high energy mixed anhydride.
  62. Step 8 of Glycolysis
    3-Phosphoglycerate -> 2-Phosphoglycerate
  63. What do the first 2 steps of step 8 make?
    a phosphoend pyruvate

    ( a molecule with high phosphoryl transfer potential)
  64. What is the function of Mutas phosphoglycerate?
    It catalyzes step 8 of glycolysis
  65. Step 9 of Glycolysis
    3-Phosphoglycerate -> Phosphoenolpyruvate
  66. Step 9 of glycolysis is catalyzed by what?
    By enolase
  67. What does the phosphate group to in step 9?
    It hold the PEP in the enol form, rather then the keto form
  68. Step 10 of Glycolysis
    Phosphoenolpyruvate-> Pyruvate
  69. What catalyzes step 10 of glycolysis?
    Pyruvate kinase
  70. Is step 10 energetically favorable or unfavorable?
    It is favorable, pyruvate is very stable compared to the enol from. and PEP has a very high transfer potential
  71. What does step 10 produce?
    the second ATP
  72. Glycolysis Produces ATP, but uses what?
    NAD+
  73. In Aerobic conditions what happens to NADH
    it is reoxidized in electron transport
  74. In anaerobic conditions what needs to happen to NAD+?
    It needs to be regenerated in order to continue producing ATP through glycolysis
  75. Lactose=?
    Galactose + Glucose
  76. Sucrose= ?
    Glucose - Fructose
  77. Gluconeogenesis
    Synthesis of glucose from pyruvate instead of carbs
  78. Does gluconeogenesis use the same enzymes as glycolysis?
    no, they each use different enzymes gluconeogenesis uses phosphatase, which removes a phosphate group.
  79. In the reaction of Pyruvate to PEP what enzyme cofactor is used?
    Biotin, to carry CO2
  80. In the reaction of Pyruvate to PEP is ATP consumed or produced?
    It consumes 2 ATP
  81. What is the biotin cofactor bound to?
    To a Lys residue
  82. What carries the biotin cofactor?
    Pyruvate carboxylase
  83. In the reaction of fructose-1,6-bisphosphate to fructose-6-phosphate how is the phosphorus released?
    It is released as PO43- instead of ATP
  84. What happens to the glucose produced by glucose-6-phosphate?
    it is released into the blood
  85. how is the glucose from glucose-6-phosphate stored?
    as glycogen
  86. Why is Glycogen metabolism regulated?
    So that sufficient glucose is available for the body's energy needs
  87. what controls glycogenesis and glycogenolysis?
    insulin, glucagon, and epinephrine
  88. what does insulin do to glycogenesis?
    it speeds it up
  89. what does glucagon do to glycogenolysis?
    it speeds it up
  90. what is the function of glycogen phosphorylase during glycogenolysis?
    it removes glucose unites from non-reducing end of glycogen until 4 are left approaching a branch point.

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