Question

Laboratory: Enzyme Activity

In this laboratory you will examine factors that affect enzyme activity.

Catalase is an enzyme found in the liver that breaks down hydrogen peroxide into water and oxygen gas. It catalyzes the following reaction:

H2O2 H2O + O2

You will examine two factors that affect its activity.

Part A: The Effect of Temperature on Enzyme Activity

Graph the volume of oxygen produced against the temperature of the solution.

How is the oxygen production in 30 seconds related to the rate of the reaction?

At what temperature is the rate of reaction the highest? Lowest? Explain.

Why might the enzyme activity decrease at very high temperatures?

Why might a high fever be dangerous to humans?

What is the optimal temperature for enzymes in the human body?

Part B: The Effect of pH on Enzyme Activity

Graph the volume of oxygen produced against the pH of the solution.

At what pH is the rate of reaction the highest? Lowest? Explain.

Why does changing the pH affect the enzyme activity?

Research the enzyme catalase. What is its function in the human body?

What is the optimal pH for the following enzymes found in the human body? Explain. (catalase, lipase (in your stomach), pepsin, salivary amylase)

I would highly appreciate if it was in a text form not handwritten.

Thank you very much.

Answer 1

At low concentrations, the graph will show an increasing rate of reaction as concentration increases, levelling off at higher concentrations. The shape is explained by the concentration of substrate directly affecting the rate of reaction until another limiting factor becomes more important

The temperature at which the rate of enzyme activity is the highest should be close to 30°C. The lowest rate of enzyme activity should be at 60°C. The rate increases as the temperature increases, until the temperature, reaches about 50°C. Above this temperature, the rate decreases.

As the temperature increases, their motion increases too. In the case of enzyme-catalyzed reactions, as the speed of enzyme and substrate molecules increases, the chance for collisions so they can form enzyme-substrate complexes increases. Thus as the temperature rises, the reaction rate increases too. Above the optimal temperature, however, this does not apply. The reaction rate begins to decrease again because some of the enzyme molecules are now warm enough so that their shape becomes altered (H bonds begin to break, denaturing the enzymes). As the temperature rises above the optimal then, an increasing number of enzymes become denatured. Fewer and fewer enzymes are able to fit with their substrates at the active site. The reaction rate decreases until at some high temperature, all the enzymes are denatured, and reactions cease.

The high fever will be dangerous to humans because, at high temperatures, most of the enzymes would become denatured as stated above.