Objectives: Take quiz on energy conversions Describe how an enzyme works

1. Objectives: • Take quiz on energy conversions • Describe how an enzyme works • Complete toothpick enzyme lab • Review Questions: • 1. What does the Law of Conservation of Energy say? • 2. What type of energy conversion does a solar panel on a house carry out? • Other Instructions: Turn in vocab., 11x17 • Coloring sheet, and fill-in-the-blank from yesterday

2. Chemical Reactions and Enzymes

3. Section 4: Chemical Reactions and Enzymes

4. Objectives • What happens to chemical bonds during chemical reactions? • How do energy changes affect whether a chemical reaction will occur? • Why are enzymes important to living things?

5. The Big Idea • Living things are made up of chemical compounds • Everything that happens to an organism is based on chemical reactions

6. Chemical Reactions • A process that changes or transforms one set of chemicals into another

7. Reactants • Elements or compounds that enter into a reaction

8. Products • Elements or compounds produced by a chemical reaction

9. Example Reaction: Getting rid of carbon dioxide • In the blood • In the lungs CO2 + H20  H2CO3 (carbonic acid) H2CO3 CO2 + H2O Released as you breathe

10. Energy-Releasing Reaction Energy-Absorbing Reaction Activation energy Products Activation energy Reactants Reactants Products Energy in reactions

11. Activation Energy • The energy that is needed to get a reaction started

13. Reason to use Catalysts • Some chemical reactions are too slow or have activation energies that are too high to make them practical for living tissue • These chemical reactions are made possible by catalysts

14. Catalyst • Substance that speeds up the rate of chemical reactions • Work by lowering a reactions activation energy

15. Enzyme • Are known as Biological catalysts • Speed up reactions in cells • Very specific name for the reaction is catylzes • Enzyme names always end in -ase

16. Reaction pathway without enzyme Activation energy without enzyme Reactants Activation energy with enzyme Reaction pathway with enzyme Products

17. Substrates • The reactants of enzyme catalyzed reactions • The active site of the enzyme and the substrate have complementary shapes • Fit like a lock and key

18. Enzyme Action Enzyme – substrate complex

19. Enzyme (hexokinase) Glucose ADP Substrates Products ATP Glucose-6- phosphate Active site Products are released Substrates bind to enzyme Enzyme-substrate complex Substrates are converted into products

20. Regulation of Enzyme Activity • Enzymes are affected by any variable that affects chemical reactions • pH • Temperature • Concentration of enzyme

21. Homework

22. What happens to chemical bonds during chemical reactions Bonds are broken in reactants and new bonds are formed in products 2. Describe the role of energy in chemical reactions some chemical reactions release energy, and other chemical reactions absorb energy. Energy changes determine how easily a chemical reaction will occur

23. 3. What are enzymes, and how are they important to living things? Enzymes are biological catylasts. Cells use enzymes to speed up virtually every important chemical reaction that takes place in cells

24. 4. Describe how enzymes work, including the role of the enzyme substrate complex Substrates, the reactants of an enzyme-catylzed reaction, attach to the enzyme at an active site and form an enzyme – substrate complex. Once the complex is formed, the enzyme helps convert substrate into product

25. 5. A change in pH can change the protein. How might a change in pH affect the function of an enzyme such as hexokinase (hint: think about the analogy of the lock and key) A change in pH could change the shape of hexokinase. This change would diminish the ability of glucose and ATP to bind to the active site of the enzyme.

26. Factors affecting Enzyme Functioning

27. Three Factors Affecting Enzyme Functioning • 1. Temperature (high and low) • 2. pH (generally low) • 3. enzyme concentration

28. Low Temperature In colder temps., the enzyme and substrate are moving slower, so they do not collide as often, causing the rate of the reaction to decrease (less products formed)

29. High Temperature • Enzyme is denatured, which means that it changes shape such that it can no longer bind to the substrate

30. Enzyme Concentration • More enzyme available (higher enzyme concentration = reaction happens faster) more product made

31. pH • Low pH tends to break hydrogen bonds, changing the shape of the enzyme (denatured) so that it can no longer bind to the substrate

32. Homework

33. What happens to chemical bonds during chemical reactions Bonds are broken in reactants and new bonds are formed in products 2. Describe the role of energy in chemical reactions some chemical reactions release energy, and other chemical reactions absorb energy. Energy changes determine how easily a chemical reaction will occur

34. 3. What are enzymes, and how are they important to living things? Enzymes are biological catylasts. Cells use enzymes to speed up virtually every important chemical reaction that takes place in cells

35. 4. Describe how enzymes work, including the role of the enzyme substrate complex Substrates, the reactants of an enzyme-catylzed reaction, attach to the enzyme at an active site and form an enzyme – substrate complex. Once the complex is formed, the enzyme helps convert substrate into product

36. 5. A change in pH can change the protein. How might a change in pH affect the function of an enzyme such as hexokinase (hint: think about the analogy of the lock and key) A change in pH could change the shape of hexokinase. This change would diminish the ability of glucose and ATP to bind to the active site of the enzyme.