Biochemistry

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icimmy
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49819
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Biochemistry
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2010-11-15 21:52:23
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Quiz 2
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  1. Why are enzymes complex?
    • Very Specific
    • Speed up reaction by factor of millions
    • Reduce energy of activation
  2. What is the Transition State?
    A state of high energy level in reaction leading to product formation.
  3. Will an enzyme work outside of it normal temperature or pH range? Why?
    • No
    • It is denatured
  4. What is the equation for equilibrium constant?
    Keq = KF[A]n/KR[B]m = [B]m/[A]n
  5. What happens at the active site of an enzyme?
    Holoenzyme - Subrate banding and catalytic activity
  6. What are the two parts of an enzyme?
    • Protein- apoenzyme
    • Non-protein - cofactor
  7. What is the lock and key model of an enzyme?
    • Enzyme- lock
    • Substrate- key
    • Doesn't take into account protein conformations.
  8. What is the induced-fit model of action enzyme?
    Assumes enzyme conformation changes to accommodate the substrate molecule
  9. How are enzymes classified?
    According to the type of chemical reaction is catalyzes.
  10. What are the six enzyme categories?
    • Oxidoreductases
    • Transferases
    • Hydrolases
    • Lyases
    • Isomerases
    • Ligases
  11. What is kinetics?
    The rate (velocity) and mechanism of a reaction
  12. How are rates usually measured?
    How many moles of reactant or product are changed per time period.
  13. What is a mechanism?
    A detailed step by step description of how a reaction occurs at the molecular level.
  14. How are all rate equations determined?
    Experimentally
  15. When the addition of more reactant has no effect on the rate what is it called?
    Zero Order
  16. What is a competitive inhibitor?
    Looks like the substrate and binds to enzyme at active site
  17. What is an uncompetative inhibitor?
    Binds only to the enzyme-substrate complex
  18. What is a noncompetitive inhibitor?
    • Doesn't look like the substrate
    • Doesn't bind at the active site
  19. What do allosteric enzymes show?
    Cooperative binding
  20. Why are transition metals useful as catalysis?
    • High positive charge
    • Accepts electrons (Lewis acid)
    • Mediate redox reaction
    • Polarize water molecules
  21. Coenzymes are organic molecules often derived from what?
    Vitamins
  22. What is the mechanism for Chymtrypsin?
    Catalyzes the hydrolysis of peptide bonds next to aromatic side chains.
  23. What are some methods that organisms use to regulate enzyme activity?
    • Genetic control
    • Covalent Modification
    • Allosteric Regulation
    • Compartmentation
  24. What is an example of enzyme induction?
    • E. coli is induced to use lactose in the absence of glucose.
    • Turned on by genetic control
  25. When the product of a biochemical pathway inhibits the functioning of a key enzyme of a previous step in the pathway it is called _______ _______?
    Enzyme repression
  26. What are the two allosteric models?
    • Concerted
    • Sequential
  27. What does the term carbohydrate mean?
    • Compounds associated with polyhydroxy
    • aldehydes -aldo
    • ketones -keto
  28. What are the names for monosaccarides with 3, 4, 5, and 6 carbons?
    • 3 - triose
    • 4 - tetrose
    • 5 - pentose
    • 6 - hexose
  29. What are enantiomers?
    Non-superimposable mirror image molecules
  30. Where are most of the oxidized carbon in a Fischer projection?
    At the top
  31. What are anomers?
    The alpha and beta forms of cyclic sugars
  32. What is cellulose?
    The major structural polymer in plants
  33. What are starches?
    Storage forms of glucose in plants
  34. What is glycogen?
    The storage carbohydrate in animals (liver and muscle cells)
  35. What is chitin?
    Provides structural support for exoskeleton in invertebrates.
  36. What is a glycoconjugate?
    Compounds that convalently link carbs to proteins and lipids
  37. What is glycolysis?
    Break down of an organic molecule (sugar) to make energy
  38. What is the net ATP formed from glycolysis?
    2
  39. What is pyruvate?
    a 3 carbon molecule
  40. What is gluconeogenesis?
    Making glucose from noncarbohydrate sources. ( 3 irreversible steps of glycolysis are bypassed)
  41. What is is called when lactate from the skeletal muscle is transferred to the liver where it is converted to pyruvate then glucose?
    Cori Cycle
  42. What is is called when pyruvate in the muscles is converted to alanine which is transported to the liven and reconverted to pyruvate?
    Alanine cycle
  43. What happens in the pentose phosphate pathway?
    • Five Carbon Sugars are produced
    • NADPH is produced for biosynthesis
    • Reshuffling of carbons to give products with 3,4, 6,7 carbons
  44. If NADPH is need, what steps must occur?
    Oxidative
  45. What reacts via the pentose phosphate pathway t make ribose?
    Fructose and glyceraldhyde
  46. What removes glucose units until 4 are left approaching a branch point?
    Glycogen phosphorylase
  47. What is central to the control of glycogen metabolism and is overall an important means of enzyme regulation?
    Covalent modification

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