1. Joe Wright Enzymes

2. Joe Wright What are Enzymes? Globular proteins Biological catalysts Do not change after reaction They are found in small quantities Specific Reactions are reversible

3. Joe Wright How Enzymes Work Enzymes lower the energy required for a chemical reaction to occur (activation energy)

4. Joe Wright How Enzymes Work

5. Joe Wright Enzyme Structure Tertiary Structure of enzyme determines its unique shape. Forms its ACTIVE SITE Active Site

6. Joe Wright Enzyme Action Enzymes work on specific substrates Substrate(s) has to fit in the active site Lock and key hypothesis Enzyme Substrate Enzyme / Substrate Complex Enzyme unchanged Products Active site

7. Joe Wright Enzyme Action Active site is sometimes flexible When substrate(s) enter active site enzyme changes shape Induced Fit Theory Enzyme Substrates Active site Enzyme / Substrate Complex Enzyme unchanged Product

8. Joe Wright Enzyme Action Rate of an enzyme reaction can be affected by: –Temperature –pH –Enzyme Concentration –Substrate Concentration

9. Joe Wright Monitoring Enzyme Action In an experiment enzyme action can be timed by: Formation of Products e.g. gas Disappearance of Substrate e.g. starch

10. Joe Wright Enzyme Activity and Temperature

11. Joe Wright Enzyme Activity and pH

12. Joe Wright Enzyme Activity and Substrate Concentration

13. Joe Wright Enzyme Activity and Enzyme Concentration

14. Joe Wright What to do now Read Key Biological Principle box page 77-79 Answer Checkpoints 2.3 and 2.4