Demonstration 3: Catalase in Turnips, Potatoes, and Rutabagas

    Purpose
        To demonstrate the activity of a typical enzyme.

    Safety
        Be careful when slicing the vegetables in the demonstration.

    Materials
        3% Hydrogen peroxide (drug store variety)
        Potatoes, turnips, rutabagas—fresh, whole; animal tissue, such as liver,
        works well

    Procedure
        Slice several potatoes, turnips, and rutabagas into 3-4 smaller pieces. Place
        each sample in a separate shallow dish. Pour sufficient 3% hydrogen
        peroxide to cover the exposed surface. Pass the dishes around to allow
        students to observe the bubbling on the cut surfaces of the vegetables. You
        might observe cut side vs. skin side of vegetables.

    Remarks
        Catalase, found naturally in the vegetables used here, reacts with the
        hydrogen peroxide to rapidly decompose it into water and oxygen gas.
        2H₂O₂ (l) => 2H₂O (l)  +  O₂ (g)
        Catalase is the enzyme that specifically decomposes hydrogen peroxide into
        water and oxygen gas. Perhaps you have noticed that when hydrogen
        peroxide is placed on an open wound, fizzing and bubbling occur. This
        reaction is caused by catalase in the blood decomposing the hydrogen
        peroxide and releasing oxygen gas.

    Reference
        Summerlin, L. (1979). Chemistry of common substances. Morristown, NJ:
            Silver-Burdett.
 

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