1. Proteins and enzymes e: Effect of temperature and pH

2. Recap Entrance ticket or whiteboard Explain how you would use Benedict’s solution to test for a reducing sugar

3. What are we learning today? We are learning to: Explain the effect of temperature on enzyme activity in terms of the shape of the active site State what is meant by term ‘optimum’ State what is meant by the term ‘denatured’

4. Experiment Aim: to find out the effect of temperature on activity of enzymes A 5mls hydrogen peroxide ice bath B 5mls hydrogen peroxide 20 o C room temp C 5mls hydrogen peroxide 40 o C water bath D 5mls hydrogen peroxide 80 o C water bath

5. Conclusion As temperature increases the activity of the enzyme increases up until temperatures around 40 o C, after which the activity decreases.

6. Explanation When enzymes are heated up they change shape: When enzymes change shape we say that they have been DENATURED This means that they will not work because the substrate will no longer fit into the active site. Enzyme working Denatured enzyme Not working

7. What is the optimum? The optimum temperature is the temperature at which an enzyme is the most active

8. What effect does pH have on enzyme activity? Enzymes have an optimum pH Enzymes have a narrow pH range at which they function

9. Effect of pH on enzyme activity Salivary amylase will not work at pH 1 and pepsin will not work at pH 9 Rate of reaction

10. Summary What does the word optimum mean? What does the word denatured mean?