enzymes: biological catalysts
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
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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. Shape based on
chemical composition & environmental conditions.
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Enzyme ReactionsMetabolism: 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)
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Example of Enzyme ReactionsLactase: Breaks down lactose (milk sugars)Pepsin: Breaks down proteinsDNA Polymerase: Adds nucleic acid bases to
growing DNA strands during DNA replication.Kinase: attaches phosphate groups; ATP production
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Enzymes speed reactions up! Chemical Rxns require reactants
collide/contactReactants ----> 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)
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Enzymes lower activation energy
ACTIVATION ENERGY = Energy needed to “jump start” rxn (energy required for rxn to proceed)
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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)
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Enzymes in Action
a. Reactant c. enzymeb. Active site d. products
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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”)
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Denaturation: Enzymes Unravel and Stop Functioning
Enzyme shape can be affected by:
Temperature pHBy interfering with bonds,
changes in temp. and pH can change enzyme shape.
Substrate does fit in active site.
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Lab: Part 1Objectives:
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.
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Lab: Part 2Objectives: 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.
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Optimal Catalase Activity
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• http://www.biologycorner.com/worksheets/enzyme_practice.html
• http://www.dnatube.com/video/307/How-enzymes-work
http://www.youtube.com/watch?v=Tn7HJphCBgcEnzymes (inhibitors, etc.)
http://www.youtube.com/watch?v=AKyyvuOmXq0&feature=related