8.5 Enzyme Activity 8.5.1 Enzyme Action LO: I understand how enzymes work.

The molecule that an enzyme acts upon is called the . substrate The substrate must fit into the site on the enzyme before the reaction to take place. active If the is too high or the is wrong, the enzyme will change . temperature pH shape It becomes and stops working. denatured LO: I understand how enzymes work.

8.5.2 The Effect of pH LO: I understand how pH affects the activity of an enzyme.

hydrogen peroxide oxygen + water Catalase is an enzyme that catalyses the breakdown of hydrogen peroxide in living cells. hydrogen peroxide oxygen + water Experiment: LO: I understand how pH affects the activity of an enzyme.

The activity of the enzyme can be measured by counting the number of oxygen bubbles produced in 3 minutes Results: pH Number of Bubbles 1 4 6 7 28 10 63 13 45 LO: I understand how pH affects the activity of an enzyme.

Graph: Number of O2 bubbles pH Conclusion: The activity of the enzyme increases with pH to an optimum at pH 10 and decreases thereafter. LO: I understand how pH affects the activity of an enzyme.

8.5.3 The Effect of Temperature LO: I understand how temperature affects the activity of an enzyme.

Results: Number of O2 bubbles Temperature (˚C) Conclusion: The activity increases with temperature to an optimum at 40˚C and thereafter decreases. LO: I understand how temperature affects the activity of an enzyme.