Pre-Laboratory Discussion

1.   Review graphing.
2.   Discuss general properties of proteins.
3.   Discuss general principles of reaction kinetics (see Reaction Rates module).
4.   Assign Procedure A or Procedure B (or both).
5.   Assign temperature to groups. Recommended temperatures are:
      Approximately 0 °C (ice bath)
      Room Temperature, 20-25 °C
      Body Temperature, 37-40 °C
      High Temperature, 70-80 °C
6.   Explain the nature of a foam (a substance that has trapped a gas).

Teacher-Student Interaction

The success of this activity requires a group effort. Students must be encouraged to
contribute their data, even if it does not seem to fit a pattern on the group graph. It
is imperative that you move from group to group to be sure that they are doing the
activities correctly and safely. Question students about their results as they are
conducting the activities.

Anticipated Student Results and Answers to Data Analysis

1.   Volume of gas (foam height) vs. time: The volume of gas (foam height) will
      increase regularly, but may tend to level off after 5 min or so.
2.   Temperature vs. volume of gas (foam height): The volume of gas (foam
      height) will increase as the temperature increases, but will drop off at higher
      temperatures.
3.   Inhibitor and enzyme: The volume of gas (foam height) will be much less, but
      may not drop to zero.

Answers to Implications and Applications

1.   This is normal body temperature. As cells evolved, they adapted to the
      temperature that would produce maximum product from enzyme action.
2.   High body temperature can inactivate protein, including the protein
      component of enzyme systems.
3.   Yes. Class data will generally show a doubling of reaction rate with each 10 °C
      increase in temperature.
4.   You would not add meat tenderizer to meat while it was cooking, since the
      thermal energy would inactivate the enzymes in the meat tenderizer. The best
      results would be in warm water. This would increase the activity of the enzymes.
      If the water were too hot, however, the enzymes would become inactivated.

Post-Laboratory Discussion

1.   If data seem to be ‘‘nonfitting” to graph, discuss experimental sources of
      error. Ask students to suggest possible sources of error.
2.   Discuss the general relationship between rates of reactions and temperature.
3.   Discuss the evidence for enzyme inhibition and gas production.
4.   Ask students to suggest applications.
 
 

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