Chemical reactions and enzymes

1. Chemical reactions and enzymes Section 2

2. Section 2 Vocabulary: ( 6 words) • chemical reaction (reactants, products), • activation energy, • catalyst, • enzyme, • substrate, • active site.

3. SC.912.L.18.11 • Explain the role of enzymes as catalysts that lower the activation energy of biochemical reactions. • Identify factors, such as pH and temperature, and their effect on enzyme activity.

4. Energy is the ability to cause change

5. Mechanical Energy • Thermal Energy • Chemical Energy • Light Energy • Sound Energy • Electrical Energy

6. Thermodynamics: the study of energy transformation

7. First Law of Thermodynamics: Energy cannot be created or destroyed; it can only be converted from one form to another • Using food for movement • Using food for maintaining body temperature • *Usable energy decreases as some is transferred to heat.

8. Energy can be stored or released by chemical reactions.

9. Chemical Equations • Reactants: substances that are combined or broken apart • Products: new substances that are formed • REACTANTS  PRODUCTS

10. Some reactions give off energy ( heat) Exergonic. The amount of energy is less at the end due to heat being released. and some take it in Endergonic! The amount of energy is greater at the end! Heat is taken in! These reactions require energy to occur!

11. Energy storing Energy releasing

13. The number before each chemical formula represents the number of molecules. The subscripts indicate the number of atoms of each element.A chemical equation is balanced when the numbers of atoms of each element are equal on each side of the arrow.2H2 + O2 2H2O

14. Respiration The chemical reaction that living things use to take glucose And oxygen and release the energy Stored in the chemical bonds And form ATP molecules while producing Water and carbon dioxide as products!

15. 1. Write the chemical reaction for respiration 2. Circle the reactants and box the products in the above reaction

16. . 3. In a balanced equation, How many molecules of glucose are used in this reaction? ONE How many molecules of oxygen are used? six

17. Activation Energy: energy needed to start a chemical reaction • Gasoline doesn’t burn on its own…it needs a spark

18. 4. What is activation energy? energy needed to start a chemical reaction

19. Enzymes Lower the activation energy!

20. Enzymes provide activation energy for the biochemical reactions in cells. • Enzymes are catalysts—they increase the rate of reactions at lower temperatures by lowering the activation energy needed. • Words that end in –ASE are enzymes.

23. enzymes

24. Substrate: molecule to which an enzyme binds • Active site: place on enzyme where substrate binds.

27. Example: Amylase catalyzes the breakdown of starch into glucose. • Enzymes attach only to certain molecules.

28. pH and temperature affect the shape of an enzyme.

29. 5. Factors that might affect the rate of an enzyme catalyzed reaction include what? • Temperature, pH, concentrations of the enzyme and substrate • Anything that alters the shape of the enzyme so that the substrate can’t fit into the active site or the availability of the enzyme.

30. 6. What does changing the pH do to an enzyme? It can break bonds between the chains of amino acids and the shape of the protein can be changed so that the active site is no longer open for bonding the substrate! This denatures the enzyme! • 7. Changing the temperature? Can do the same as pH it can break the hydrogen bonds that hole a protein in the proper shape and denature the enzyme!

31. 8. The major role of an enzyme in biochemical reactions is what? • They lower the energy of activation! This allows chemical reactions to take place at greater rates and lower temperatures.

32. 9. What is the active site of an enzyme? • The place on the enzyme where the substrate binds! an enzyme: protein that lowers the activation energy! Catalyst!

33. 10. Draw a graph of an enzyme catalyzed reaction and a reaction without

34. Title: Factors Affecting Reaction Rates Problem: How will concentration, temperature and a catalyst affect the rate of a chemical reaction? Background /Introduction: In a reaction where the reactants have more potential energy then the products it should occur spontaneously and give off heat. This type of reaction is called exothermic in thermodynamics. However, not all of these reactions are spontaneous because the reactants must collide with each other with enough force and frequency to exceed a critical energy level to get the reaction started. This critical energy level is called the activation energy.

35. To increase the rate of a reaction one of 2 things must occur: (1) more molecules with kinetic energy must be present to get the number of collisions needed to get over the “hump” (2) the activation energy must be decreased.

36. There are 2 ways to get more molecules to collide. Increase the number of molecules and increase the temperature. To lover the activation energy a catalyst may be added. The catalyst participates in the reaction but is not consumed by the reaction. The rate of the catalyzed reaction is faster because the activation energy is lowered by the presence of the catalyst.

37. Hypothesis: • How do you think changing the concentration will affect the rate of the reaction? • How do you thing changing the temperature will affect the reaction rate? • How do you think adding a catalyst will affect the reaction rate?