Biology Enzyme Lab

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Lab 6

Report by Mary Jo Anthony

I. Introduction
II. Materials and Methods
III. Results
IV. Conclusion and Discussion

Background Information:
This lab allowed us to study chemical reactions and how catalysts will affect the rate of these reactions. The reaction we studied is the breakdown of hydrogen peroxide to water and oxygen and it is vital to life. The molecule hydrogen peroxide is a molecule that is toxic to cells but is also a by product of various cellular activities. (Lab Manual) The breakdown of these molecules to water and oxygen is a slow process. However, the breakdown of hydrogen peroxide inside the cell happens very quickly. This breakdown within the cell happens so quickly because of an enzyme called catalase. Catalase is produced in most cells of the body and the breakdown of hydrogen peroxide can occur with a smaller amount of energy when this enzyme is present. For this lab, we used catalase from beef. In order for chemical reactions to occur they have to be given enough time or extra energy in the form of heat, or both. By adding a catalyst to the reactants, the reactions, can be sped up or may require less energy input. A catalyst is a “chemical agent that selectively increases the rate of a reaction without being consumed by the reaction”. (Campbell p.152) Catalysts may be reused several times. The reason we use a catalyst is to lower the energy of activation of the reaction. Energy of activation is defined as “the energy required to get the reactions started”. (Lab Manual) Metabolism in living organisms must be conducted quickly and at temperatures low enough to prevent the organism from dying. Using organic catalysts, such as enzymes (protein-based molecules), allows this to occur. Each enzyme in living organisms is specific to a particular kind of reaction and without these enzymes; critical reactions could not take place because they would cause severe damage to the organism. The three-dimensional shape of the enzyme is the reason for their specificity. The enzyme acts on its substrate which binds to the enzyme’s active site. Enzymes are very specific because they can recognize their specific substrate even among closely related compounds. The chemical bonds can be broken with less energy input because the enzymes can cause stress on the bonds. Many factors such as temperature, pH, and concentrations of the enzyme and/or substrates can affect the efficiency of an enzyme. The activity of an enzyme is governed by the three-dimensional shape of a protein. This means that a change in the shape of the protein will affect the efficiency of the enzyme. “A permanent change in or destruction of the three-dimensional shape of an enzyme or protein is called denaturation”. (Lab Manual) Denaturation to enzymes is caused by extreme temperatures and pH.

This labs purpose was for us to obtain a better understanding of how enzymes function and how temperature and pH can affect the rates and functions of an enzyme’s reaction.

For the effects of temperature:
H0: Temperature will not affect the rate of the enzymatically-driven breakdown of hydrogen peroxide by the catalase. HA: Temperature will affect the rate of the enzymatically-driven breakdown of hydrogen peroxide by the catalase.

For the effects of pH:
H0: The enzymatically-driven breakdown of hydrogen peroxide will not be affected by the pH. HA: The enzymatically-driven breakdown of hydrogen peroxide will be affected by the pH.

My expectations for this lab were that enzymatically-driven breakdown would be affected by temperature and pH because it is proven that extremes in both temperature and pH cause an enzyme to denature.

Materials and Methods
The materials used in each group for this experiment were one reaction chamber, one curved-tip forceps, one square or rectangular tub...
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