1. Enzymes

2. Enzymes are Catalysts Catalysts lower the activation energy of a reaction. Catalysts lower the activation energy of a reaction. Makes the reaction easier Makes the reaction easier Catalysts increase the rate of reaction. Catalysts increase the rate of reaction. Speeds the reaction up Speeds the reaction up

3. Enzymes Biological Catalysts Biological Catalysts Catalysts found in living things Catalysts found in living things

4. Names of Enzymes End in –ase End in –ase Examples: Examples: Amylase Amylase Catalase Catalase RNA Polymerase RNA Polymerase

5. Structure and Function Lower the activation energy Lower the activation energy Increase the rate of reaction Increase the rate of reaction

6. Homeostasis and Enzymes Breaking down food Breaking down food amylase breaks down starch in your mouth amylase breaks down starch in your mouth Building other proteins Building other proteins Used in your immune system Used in your immune system

7. Substrates The “things” the enzyme acts on, or breaks down The “things” the enzyme acts on, or breaks down Amylase breaks down only starch Amylase breaks down only starch Have activation sites, that fit into the enzyme Have activation sites, that fit into the enzyme

8. Lock and Key Model E = Enzyme S = Substrate P = Product + + + + E + S ES complex E + P E + S ES complex E + P S P P S

9. Enzyme Action: Lock and Key Model 1. An Enzyme brings the substrate molecule close together 2. Enzyme decreases activation energy 3. An enzyme binds a substrate in a region called the active site 4. Enzyme-substrate complex forms 5. Substrate reacts to form product 6. Product is released

10. Factors Affecting Enzymes High Temperatures can DENATURE enzymes (breaks down) High Temperatures can DENATURE enzymes (breaks down) Substrate/Enzyme Concentrations can slow enzymes down Substrate/Enzyme Concentrations can slow enzymes down pH can affect enzymes pH can affect enzymes

11. Factors Affecting Enzyme Action: Temperature Little activity at low temperature Little activity at low temperature Rate increases as temperature increases Rate increases as temperature increases Most active at optimum temperatures (usually 37°C in humans) Most active at optimum temperatures (usually 37°C in humans) Activity lost with denaturation at high temperatures Activity lost with denaturation at high temperatures

12. Factors Affecting Enzyme Action Optimum temperature ReactionRate Low High Low High Temperature Temperature

13. Factors Affecting Enzyme Action: Substrate Concentration Increasing substrate concentration increases the rate of reaction (enzyme concentration is constant) Increasing substrate concentration increases the rate of reaction (enzyme concentration is constant) Maximum activity reached when all of enzyme combines with substrate Maximum activity reached when all of enzyme combines with substrate

14. Factors Affecting Enzyme Action Maximum activity ReactionRate substrate concentration substrate concentration

15. Factors Affecting Enzyme Action: pH Maximum activity at optimum pH Maximum activity at optimum pH Most lose activity in low or high pH Most lose activity in low or high pH

16. Factors Affecting Enzyme Action ReactionRate Optimum pH 3 5 7 9 11 3 5 7 9 11pH