1. Enzymes

2. Chemical Reactions In order for chemical reactions to take place, enzymes must be present to help speed up the reaction. Chemical bonds connect atoms to make molecules. Chemical reactions can do two things:  They can join atoms to make molecules.  They can break bonds in molecules. The sum of all the chemical reactions that take place within a cell is referred to as the cell’s metabolism.

3. Chemical Reactions The molecules or atoms at the beginning of a chemical reaction are called the reactants. The materials produced by the chemical reaction are called products. 2H 2 + O 2  2H 2 O Reactants Product

4. Law of Conservation of Matter/Energy Matter and Energy cannot be created or destroyed in chemical reactions

5. Energy-Absorbing vs. Energy-Releasing Reactions Energy-Absorbing Reaction Endothermic Reaction Energy-Releasing Reaction

6. The molecules or atoms at the beginning of a chemical reactions are called ______. A. Enzymes B. Reactants C. Products D. Active sites

7. Chemical reactions in which the products have more energy than the reactants are called _________ reactions. A. Energy-Releasing B. Energy-Absorbing

8. Which graph illustrates an energy-releasing reaction? A. Graph A B. Graph B

9. Introduction to Enzymes Enzymes are proteins that act as biological catalysts.  Catalysts - speed up chemical reactions.  Enzymes- speed up chemical reactions in living things.

10. Structure and Function of Enzymes A substrate is the molecule that the enzyme changes.  It is the reactant a chemical reaction controlled by an enzyme! Each enzyme has an active site which is the place where the enzyme and substrate attach.

11. Structure and Function of Enzymes During a chemical reaction, the enzyme helps the reactant turn into product, however, the enzyme is not changed. Enzymes can be used over and over again. Reactant/Substrate   Product Enzyme  No change in the shape of enzyme/ready to catalyze next reaction.

12. Enzymes are specific types of which biological macromolecule? A. Carbohydrates B. Proteins C. Lipids D. Nucleic acids

13. The molecule on which an enzyme acts: A. Catalyst B. Substrate C. Metabolism D. Homeostasis

14. Which shape is the enzyme? 1. A 2. B 3. C 4. D AAA B C DD

15. Which shape is the product of the chemical reaction shown below? 1. A 2. B 3. C 4. D AAA B C DD

16. Enzyme Specificity Enzymes are very specific. This means that each enzyme can only work on one substrate.  For example:  1. Maltase only breaks down maltose (a carbohydrate).  2. Lipase only works on certain lipids.  3. Protease only works on certain proteins. Does a specific enzyme work on more than one substrate? NO!!!

17. Enzyme Specificity Therefore you need thousands of different enzymes for the thousands of different chemical reactions in your body. The names of many enzymes (Amylase, Lipase, Pepsin, Trypsin) usually end in ase or in.

18. Enzyme Specificity The diagram below shows the lock and key model of how enzymes work on a specific substrate. Just like every lock has one type of key that opens it, every substrate has one type of enzyme that works on it.

19. How Enzymes Work Lower activation energy  Energy that is needed to start a chemical reaction  Puts substrates in a good position to make/break bonds with each other

20. Reaction with enzyme vs. Reaction without enzyme

21. The energy that is required to start a chemical reaction is called A. Endothermic energy B. Exothermic energy C. Enzyme energy D. Activation energy

22. How do catalysts speed up or facilitate chemical reactions? A. Lower the activation energy B. Add energy to the reaction C. Break hydrogen bonds in the chemicals D. Decrease the number of reactants

23. Enzymes lower activation energy

24. Enzymes and Their Environment Most cells function best within a narrow range of temperature and pH. At very low temperatures, enzymes work too slow.

25. Enzymes and Their Environment At high temperatures or extremes of pH the enzymes lose their shape.  What would happen if a key lost its shape? It wouldn’t turn or fit in the hole.  What will happen if an enzyme lost its shape? It wouldn’t recognize or bind with it’s substrate.

26. Enzymes and Their Environment When an enzyme loses its shape and can no longer work correctly, it has been denatured.

27. Enzymes stop functioning if: A. They act on a substrate B. They become denatured due to improper pH or temperature C. They catalyze too many reactions D. They bind with the wrong substrate

28. When proteins, such as enzymes, lose their specific shape they have become __________. A. Passive B. Endothermic C. Exothermic D. Denatured

29. What is the optimum pH for the enzyme pepsin? A. 1 B. 2.5 C. 5 D. 6.5 pepsin trypsin