Catalase Laboratory

Advanced Placement Biology

 

Problem:  To investigate the activity of the catalase enzyme.

 

Introduction:  Catalase is an enzyme active in all cells.  It acts in the reaction that breaks down hydrogen peroxide into water and oxygen gas.  All cells break down hydrogen peroxide and convert it into harmless substances.

 

                                                  2H2O2                2H2O   + O2

 

In this experiment the enzyme,catalase, is in the yeast suspension .  The hydrogen peroxide solution is the substrate.  Filter paper discs are dipped into the yeast suspension.  A small vial is filled with hydrogen peroxide solution.  The disc is dropped into the solution.  It falls to the bottom of the vial.  As the reaction occurs, the oxygen produced in the reaction infiltrates the disc causing the disc to rise to the surface of the hydrogen peroxide solution.  This is called a clock reaction because the time for the reaction is indicative of enzyme’s activity.

 

Directions:  Obtain the following supplies for your desk.

  1. Beaker containing yeast suspension
  2. Hydrogen peroxide solutions
    1. Different concentrations( dilutions)
    2. Different temperatures: 4oC, 22oC, 37oC, and 60oC.
    3. pH variations

 

  1. Forceps
  2. Glass vials
  3. Stop watch

 

Part One.  Calibration at room temperature

Practice your procedure

 

  1. Dip the disc into the yeast suspension
  2. Drop the disc into the hydrogen peroxide solution
  3. Start your timing
  4. When the disc reaches the surface of the hydrogen peroxide solution stop the watch and record the data in your table below.
  5. Repeat at least three times.  Find the average.  If your results are not consistent, they must be repeated until all results are similar.

 

Temperature

Trial 1

Trial 2

Trial 3

Average

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Graph your data.

 

Part Two:  Substrate Concentration.  Test enzyme activity by using different concentrations of hydrogen peroxide solution.  Record the data in your data chart.

 

Substrate concentration

Trial 1

Trial 2

Trial 3

Average

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Graph your data.

 

 

Part Three.  PH.  To study pH use the different solutions at the supply table to determine the effect of pH on the activity of the catalase enzyme

 

 

pH of the hydrogen peroxide solution

Trial 1

Trial 2

Trial 3

Average

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Graph your data.

 

Discussion:

 

  1. How does temperature effect enzyme activity?  What happens at 60oC?  Why?
  2. Relate your results to the lock and key, enzyme and substrate model of activity.
  3. What organisms that we have studied this year are able to withstand temperatures greater than 55oC ? How do their enzymes differ from our enzymes?
  4. What is the optimal pH for catalase enzyme activity?
  5. State the relationship between enzyme activity and substrate concentration.