Enzymes are globular proteins, responsible for most of the chemical activities of living organisms. They act as catalysts, substances that speed up chemical reactions without being destroyed or altered during the process. Enzymes are extremely efficient and may be used over and over again. One enzyme may catalyze thousands of reactions every second.

H2O2 is toxic to most living organisms. Many organisms are capable of enzymatically destroying the H2O2 before it can do much damage. H2O2 can be converted to oxygen and water, as follows:

{\text{2 }}{{\text{H}}_{\text{2}}}{{\text{O}}_{\text{2}}} \to {\text{2 }}{{\text{H}}_{\text{2}}}{\text{O + }}{{\text{O}}_{\text{2}}}

Although this reaction occurs spontaneously, enzymes increase the rate considerably. Catalase, a common enzyme that is found in the cells of nearly all living organisms, catalyzes the decomposition of H2O2. A great deal can be learned about enzymes by studying the rates of enzyme-catalyzed reactions.


In the Preliminary Activity, you will use catalase in yeast to catalytically decompose hydrogen peroxide. You will determine the rate of enzyme activity by measuring the pressure of oxygen gas produced as H2O2 is decomposed.

After completing the Preliminary Activity, you will first use reference sources to find out more about enzymes and enzyme activity before you choose and investigate a researchable question dealing with enzyme activity.