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Catalase Reactions: Measuring Enzymatic Rates

This lab demonstrates the structure and function of enzymes.

What would happen to your cells if they made a poisonous chemical? You might think that they would die. Interestingly enough, your cells are always making poisonous chemicals, and not dying. This is because your cells use proteins known as enzymes to speed up the conversion of these poisonous chemicals into harmless ones that are useful.

All of the enzymes in your body are responsible for one specific chemical reaction. The chemical reaction of this lab is the breakdown of hydrogen peroxide (H2O2) by an enzyme known as catalase (KAT-uhLAYSS). When hydrogen peroxide accumulates inside cells, it becomes extremely poisonous and could result in cell death. Therefore, cells rely on catalase to convert hydrogen peroxide into nontoxic molecules of water and oxygen.

In this lab, you will compare catalase’s rate of reactions in three different living things. A rate of reaction is how fast a chemical reaction occurs. When there is more enzyme present, the rate of reaction will be much faster. This is because enzymes speed up chemical reactions. Likewise, when there is less enzyme present or the enzyme no longer works, the rate of reaction will be much slower or close to zero.

Enzymes can stop working when they are placed in extreme conditions (heat) outside of their optimum range. This is known as denaturation. Denaturation changes the shape of the enzyme’s active site, meaning the enzyme and substrate no longer complement one another. As a result, binding does not occur and the chemical reaction will not take place. Hence, a reaction rate of 0.


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