Lab 2: Enzyme Catalysis

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  1. What effect does salt concentration have on enzymes?
    • too low: the charged amino acid side chains attract each other and denature enzyme forming inactive precipitates
    • too high: nteraction of charged groups will be blocked, and newinteractions occur; precipitates form
  2. What effect do activators and inhibitors have on enzymes/
    • activators: increase rate of reaction
    • inhibitors; decrease rate of reaction
  3. What is the primary reaction catalyzed by catalase?
    H2O2 --> H2O + O2
  4. The slope of the graph line during hte early period in whic the enzyme acts on the substrate at a constant rate is calle dhte __ of the reaction.
    initial rate
  5. How do you determine rate?
    • delta y/ delta x
    • - divide the difference between two poitns on y axis by difference of same two points on x axis
  6. How may the rate of a reaction be studied?
    • amount of disappearance of substrate
    • amount of heat given off or absorbed
    • amount of product formed
  7. Briefly describe the experiment and what is used.
    Catalase is placed in a beaker with H2O2. At a given time period, sulfuric acid is added to stop the reaction and denature the enzyme. To determine how much H2O2 is left, we used potassium permanganate to titrate the sample of H2O2 left. We add titrate till its a faint pink or brown color.
  8. What is the enzyme in the reaction?
    how do you know the gas evolved in O2?
    • catalase
    • H2O2
    • H2O and O2
    • a chemical change occurred (O2 appeared as bubbles)
  9. Before you do the experiment, what do you need?
    • a baseline
    • - put H2O2 with water without enzyme, sulfuric acid and titrate
  10. As time passes, what would you expect to happen to H2O2?
    Wat does this mean for potassium permanganate? Why?
    • there would be less H2O2 left over, resulting in less potassium permanganate used because the more H2O2 left oer, the more potassium permanganate is used to change it ot a pink color because the H2O2 decomposes it.
    • The more H2O2 consumed, the less potassium permanganate is needed to titrate.
  11. What is the independent and dependent variables?
    How would the graph look?
    • inde: time
    • depend: amount of H202 consumed
    • - it should go upward and eventually balance out.
  12. When is the rate the highest and why?
    THe rate is highest in the beginning because there is a great amount of substrate. WIth more substrate, once a substrate is converted into a product, another substrate quickly occupies the active site. The shorter hte reaction, the more peroxide is left over.
  13. When is the rate the lowest? Why?
    at the end because most of hte substrate has been converted to product already; all of it has been consumed already; there isn't much substrate and it is possibel that the products are preventing some substrate from occupying the active site. THe longer the time, the slower hte reaction and the less peroxide left over.
  14. Why can sulfuric acid inhibit an enzyme?
    becuase it makes the pH more acidic
Card Set
Lab 2: Enzyme Catalysis
AP Bio
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