Physiology Ch.4

  1. Enzymes
    • Most enzymes are proteins
    • Have specific shapes, so they don't have the same shape
    • Named according to their job/activity
    • Can be measured in a clinical laboratory to look for disease
    • Functionally are biological catalysts
  2. Biological catalysts
    • Chemicals that increase the rate of reaction
    • Are not changed at the end of the reaction (structure not changed)
    • Do not change the nature of the reaction or final result
    • Lower the activation enery required
  3. Mechanism of Enzyme Action
    • Substrates have specific shapes (3-dimensional) to fit into the active sites (lock and key model)
    • Substrate fits into active sites in enzyme
    • ----all happening inside the cell
  4. Control of Enzyme Activity
    The rate of enzyme-catalyzed reaction depends on:
    • Concentration of the enzyme in the solution
    • Temperature of the solution in which the reaction is occuring
    • Ph of the solutiion in which the reaction is occuring
    • Concentration of coenzymes/cofactors (helpers) in the solution (helps enzymes to be more efficient
  5. Effect of temperature
    • Rate of reaction increases as temperature increases from 0 C up to 37 C
    • Reaction rate plateaus, slightly above body temperature (37 C)
    • Above 37 C reaction rate decreases as the temperature continues to increase
  6. Summary of temperature on enzyme activity
    From 0 C reaction rate is very slow, it progressively increases as the temperature increases but them plateaus at 37 C (body temp) and then decreases again as the temperature continues to increase
  7. Effect of pH
    • Each enzyme exhibits peak activity at narrow pH range (pH optimun)
    • pH optimum reflects the pH of the body fluid in which the enzyme is found
    • If pH changed, so is no longer within the enzyme range; reaction will decrease
  8. Summary of pH on enzyme activity
    Each enzyme has a pH optimun and an increase or decrease in pH can slow down the reaction time
  9. Enzyme Activation
    • Enzymes may be produced in an inactive form
    • Phosphorlation/dephosphorylation (Activation/inactivation of an enzyme)
  10. Metabolic Pathways
    • Sequence of enzymatic reactions that begins with initial substrate, progesses through intermediates and ends with a final product (like an assembly line)
    • Thousands of enzymatic reaction within a cell do not occur independently of one another-instead they are all connected and effect one another (like branches on a tree)
Card Set
Physiology Ch.4
Ch. 4 enzymes and energy