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Enzymes: Biological Catalysts. Special group of biomolecules, usually proteins. Help make chemical reactions happen … rxns necessary for life functions! “ Biological catalysts ” - speed up rates of reactions Function based on shape.

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Enzymes: Biological Catalysts

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    1. Enzymes: Biological Catalysts • Special group of biomolecules, usually proteins. • Help make chemical reactions happen … rxns necessary for life functions! • “Biological catalysts” - speed up rates of reactions • Function based on shape. • Shape based on chemical composition & environmental conditions.

    2. Enzyme Reactions Metabolism: Complete set of chemical rxns in a body. Enzymes catalyze these rxns. Divided into 2 types of rxns: a. Catabolic: Lg. Complex molecules broken down to simpler ones & release energy. b. Anabolic: Building larger molecules fr. Smaller ones (energy input)

    3. Example of Enzyme Reactions Lactase: Breaks down lactose (milk sugars) Pepsin: Breaks down proteins DNA Polymerase: Adds nucleic acid bases to growing DNA strands during DNA replication. Kinase: attaches phosphate groups; ATP production

    4. Enzymes speed reactions up! • Chemical Rxns require reactants collide/contact Reactants ----> Products • Enzymes make it easier for reactions to occur by putting stress on specific bonds or atoms w/in molecules. • Lower ACTIVATION ENERGY needed for rxns. To procede (These rxns would occur anyway, but @ slower rate)

    5. Enzymes lower activation energy ACTIVATION ENERGY = Energy needed to “jump start” rxn (energy required for rxn to proceed)

    6. Enzyme-Substrate Complex Substrate = Reactant molecules; fit into enzymes. ACTIVE SITE: Location where substrate binds. Enzyme will only bind to specific substrates based on SHAPE! (Lock & Key fit)

    7. Enzymes in Action • Reactant c. enzyme • Active site d. products

    8. Enzyme shape is important to fxn Enzyme fxn depends on shape of active site. Shape of enzyme can be affected by … • Temperature? • pH? • Presence of other binding molecules (inhibitors or “helpers”)

    9. Denaturation: Enzymes Unravel and Stop Functioning Enzyme shape can be affected by: • Temperature • pH By interfering with bonds, changes in temp. and pH can change enzyme shape. Substrate does fit in active site.

    10. Lab: Part 1 Objectives: 1. Observe reaction catalyzed by CATALASE. H2O2 ----------------------> H2O + O2 Hydrogen Peroxide water oxygen 2. Determine if enzymes are reusable or are they changed by the reactions they catalyze.

    11. Lab: Part 2 Objectives: 1. Determine the optimal temperature and pH conditions of catalase. H2O2 ----------------------> H2O + O2 Hydrogen Peroxide water oxygen 2. Identify conditions that cause denaturation and explain how denaturation influences enzyme activity.

    12. Optimal Catalase Activity

    13. http://www.biologycorner.com/worksheets/enzyme_practice.html • http://www.dnatube.com/video/307/How-enzymes-work http://www.youtube.com/watch?v=Tn7HJphCBgc Enzymes (inhibitors, etc.) http://www.youtube.com/watch?v=AKyyvuOmXq0&feature=related