Biology 172 Lecture 5

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Biology 172 Lecture 5
2012-01-26 21:10:16
Biology 172 Lecture exam review

Biology 172 Lecture 5 exam review
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  1. In an alpha heliex R group ...
    faces out
  2. _______ makes a kink in the polypeptide chain
  3. Higher Free Energy
    • Less stable
    • More concentrated
    • More ordered
    • Greater work capacity
  4. Lower Free Energy
    • More stable
    • Less concentrated
    • Less ordered
    • Less work capacity
  5. Objects tend to move from ....
    Higher free energy to lower free energy
  6. Free energy describes a _______ _______
    biological state
  7. Some biological states have higher free energy characterized by .....
    Biological events are driven by movement from higher free energy to lower free energy
  8. A catalyst changes the ....
    Activation energy of a Reaction
  9. Characteristics of Enzyme Action
    • Enzymes are substrate-specific
    • Region that binds substrate is active site
    • Binding involves interactions between enzyme's R-group and substrate
    • Binding destabilizes bond(s) in substrate
  10. What happends to the enzymes shape
    it changes temporarily
  11. Interactions with R-groups at active site ....
    stabilize tansition state
  12. What do enzymes do?
    • Active site binds substrate (reactants) -> substrate specifcity
    • Binding involves interactions between enzyme's R-groups and substrate
    • Binding destabilizes chemical bonds in substrate -> lowers the activation energy -> reaction goes faster
  13. Enzymes do not ....
    Enzymes do .....
    • add energy to the reaction
    • Decrease the energy of activation for exergonic reactions
  14. Specificity
    induced fit between enzyme and its substrate
  15. Reactant Molecules Bind to ....
    Specific Locations in and Enzyme
  16. Interactions in the active site ...
    (e.g. H bonding, charge interactions) stabilize the transition state
  17. Factors that affect proteins ...
    affect enzymes and thus affect the rate of a reaction
  18. reaction rate =
    amount of product formed (or substrate used) / time
  19. Factors Affecting the Rate of a Reaction
    • Substrate concentration
    • Enzyme concentration
    • Temperature
    • pH (and the concentration of other ions)
  20. Environmental factors that affect the rate of reaction
    • Enzymes from different organisms may function best at different temperatures
    • Enzymes from different organisms may function best at different pHs

  21. Isozymes
    Catalyze same reaction but have slightly different structures and/or localizations
  22. Different substrates
    • Enzymes may have different or NO affinity for different substrates
    • Different substrates look different
    • May or may not fit active site
    • Enzyme might or might not 'like' different substrates
  23. Enzyme Km Depends on ....
    Affinity for Substrate
  24. Substrate with highest affinity for enzyme (best fit for active site) will produce ...
    1/2 Vmax at lowest Km
  25. Higher Km means
    lower affinity
  26. Km describes ...
    the affinity of an enzyme for its substrate
  27. A low Km means ...
    that the enzyme holds the substrate tightly (high affinity) and is very efficient at converting it to product
  28. A high Km means
    that the enzyme holds the substrate more loosely (lower affinity) and is less efficient at converting it to product
  29. Cofactors =
    • small non-protein molecules
    • Usually inorganic (metals) ions (prosthetic groups) such as Mg2+, Ca2+, Cu2+, Mn2+, Zn2+, Fe2+3+
  30. Coenzymes
    • sometimes organic
    • NAD+, CoA, Vitamins
  31. Enzymes can only catalyze reactions that are ...
    • ultimately "downhill"
    • ie. where delta G is negative