2. 1 Enzymes Enzyme and Digestion film clip Enzyme and Digestion film clip

3. 2 What Are Enzymes? Most enzymes are Proteins Act as Catalyst to accelerates a reaction Not permanently changed in the process

4. 3 Enzymes Are specific for what they will catalyze Are Reusable End in – ase -Sucrase -Lactase -Maltase - Lipase - Protease

5. 4 How do enzymes Work? Enzymes work by weakening bonds which lowers activation energy

6. Enzymes Lower a Reaction’s Activation Energy Activation Energy = energy needed to start a chemical reaction

7. 6 Enzymes Free Energy Progress of the reaction Reactants Products Free energy of activation Without Enzyme With Enzyme

8. 7

9. 8 Enzyme-Substrate Complex The substance (reactant) an enzyme acts on is the substrate Enzyme Substrate Joins

10. 9 Active Site An Active site of an enzyme molecule is where the substrate binds. Enzyme Substrate Active Site

11. 10 Two ways in which Enzyme and substrates bind 1. Lock and key model 2. Induced fit model

12. 11 Lock and Key Model + + E + S ES complex E+ P S P P S E = Enzyme S = Substrate P= product Active site

13. Lock & Key Model One enzyme for every substrate unique fit Substrate Enzyme

14. The enzyme fits over the substrate perfectly – like a key fits a lock. It holds the starch molecule in place as a water molecule breaks the bond between two glucose particles Starch molecule Amylase enzyme

15. This continues until the molecule has been broken down completely

16. 15 Induced Fit A change in the shape of an enzyme ’ s active site Induced or altered by the substrate

17. The active site of an enzyme is where substrate is bound. Many Enzymes Work by Altering the Shape of Their Substrates

18. 17 Enzyme Action: Induced Fit Model Enzyme structure flexible, not rigid Enzyme and active site adjust shape to bind substrate

19. 18 Enzyme Action: Induced Fit Model E + S ES complex E + P S P P SS

20. 19 Factors Affecting Enzyme Activity Temperature pH Cofactors & Coenzymes Inhibitors

21. 20 Temperature & pH High temperatures are the most dangerous reactions & denature enzymes (Most like normal Body temperatures) Most enzymes like near neutral pH (6 to 8) Denatured (unfolded) by ionic salts and metal ions

22. 21 Factors Affecting Enzyme Action Optimum temperature Reaction Rate Low High Temperature

23. 22 Factors Affecting Enzyme Action Reaction Rate Optimum pH 3 5 7 9 11 pH

24. 23 Cofactors and Coenzymes Inorganic substances (zinc, iron) and vitamins (respectively) are sometimes need for proper enzymatic activity. Example: Iron must be present in the protein structure of hemoglobin in order for it to pick up oxygen.

25. 24 Factors Affecting Enzyme Action Maximum activity Reaction Rate substrate concentration

26. Digestive Enzymes There are 3 main types of digestive enzymes: –Amylase breaks starch down into glucose. –Protease breaks protein down into amino acids. –Lipase breaks fats down into fatty acids and glycerol

27. Digestive Enzymes Amyla se Starch Glucose Protea se Protein Amino Acids

28. Digestive Enzymes Glycerol Fatty Acid Glycerol Fatty Acid Lipase Fat Fatty Acids and Glycerol

29. 28 Enzyme Inhibition Inhibitors Cause a loss of catalytic activity Change the protein structure of an enzyme May be competitive or noncompetitive Some effects are irreversible Poisons and drugs are examples of enzyme inhibitors.

30. 29 Competitive Inhibition A competitive inhibitor Has a structure similar to substrate Occupies active site Competes with substrate for active site Has effect reversed by increasing substrate concentration

31. 30 Noncompetitive Inhibition Does not have a structure like substrate Binds to the enzyme but not active site Changes the shape of enzyme and active site Substrate cannot fit altered active site No reaction occurs Effect is not reversed by adding substrate