Catalase Enzyme Lab
Background information
Liver and other living tissues contain the enzyme catalase. This enzyme breaks down hydrogen peroxide,
which is a harmful by-product of the process of cellular respiration if it builds up in concentration in the
cells. If we use potato or other tissue containing this enzyme, we can use this to measure the relative
influence of varying several different factors on the activity of enzymes in living tissue.
In order to obtain energy and building blocks from food, the digestive system must break down proteins,
fats and carbohydrates. In this process, specific enzymes catalyze hydrolysis reactions in which food
polymers are broken up into monomers. In this lab, you will perform reactions involved in digestion of
carbohydrates, lipids, and proteins and observe the results of these reactions.
INTRODUCTION: What would happen to your cells if they made a poisonous chemical? You might think
that they would die. In fact, your cells are always making poisonous chemicals. They do not die because
your cells use enzymes to break down these poisonous chemicals into harmless substances. Enzymes are
proteins that speed up the rate of reactions that would otherwise happen more slowly. The enzyme is not
altered by the reaction. You have hundreds of different enzymes in each of your cells.
Each of these enzymes is responsible for one particular reaction that occurs in the cell. In this lab, you
will study an enzyme that is found in the cells of many living tissues. The name of the enzyme is catalase
(KAT-uh-LAYSS); it speeds up a reaction which breaks down hydrogen peroxide, a toxic chemical, into 2
harmless substances--water and oxygen.
The reaction is as follows: 2H2O2 ----> 2H2O + O2 (fix)
This reaction is important to cells because hydrogen peroxide (H2O2) is produced as a byproduct of many
normal cellular reactions. If the cells did not break down the hydrogen peroxide, they would be poisoned
and die. In this lab, you will study the catalase found in liver cells. You will be using chicken or beef liver.
It might seem strange to use dead cells to study the function of enzymes. This is possible because when
a cell dies, the enzymes remain intact and active for several weeks, as long as the tissue is kept
refrigerated.
MATERIALS:
6 Test tubes and Test tube holder
10-ml Graduated cylinder
40 ml 3% Hydrogen peroxide solution (found in
stores)
Sodium Bicarbonate
Straight-edged razor blade
Scissors and Forceps (tweezers)
Thermometer
Stirring rod
pH paper
Hydrochloric Acid
Fresh liver, chicken meat, Apple, and Potato
