Concept: Enzymes are proteins that assist metabolic reactions and enable them to take place at lower temperatures or higher rates, as required by different circumstances. The presence, concentration, or absence of enzymes can determine the rate at which a reaction occurs — or whether it occurs at all. Enzymes can be denatured or rendered ineffective by temperature changes or interactions with acids and bases.
Perform Illustrated Guide to Home Biology Experiments, Lab III-3, Procedures 1 and 2 (we will do measurements of Vitamin C in another lab).
Perform the Catalase Lab designed by Gen Nelson at Access Excellence, which has instructions on how to make your own catalase solution from potatoes. You may also find the instructions for the Flinn Scientific version of the this experiment useful in planning your procedure. If you prefer commercial catalase, it is available from several suppliers on my science supplies list.
Pay particular attention to all safety instructions!
The lab contains a method for preparing a catalase extract from potatoes, as an alternative to commercial catalase. Also, instead of using potassium permanganate to measure the presence of H2O2, the lab uses a "floating filter" measure of O2 production, which is, of course, proportional to the disappearance of hydrogen peroxide.
You can skip the section on the effects of pH on enzyme activity, OR use the following substitutes for the pH variations. To make solutions from baking soda and cream of tartar, put 1 tsp. in 1/4 C distilled water and dissolve completely.
|Vinegar or Lemon Juice
|Cream of Tartar solution
|Baking Soda solution
If you cannot manage to work through the Access Excellence lab, then work the Enzyme Activity Simulation lab and record your data for enzyme activity for maltase and amylase as they break down starch and maltose to glucose.
Fill out the lab report data tables and answer the questions for the lab you perform (AP, IGHBE, or Access Excellence). Leave any columns for class averages blank; we will do those together.
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