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.

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)

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

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)

Enzymes lower activation energy

ACTIVATION ENERGY = Energy needed to “jump start” rxn (energy required for rxn to proceed)

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)

Enzymes in Action

a. Reactant c. enzymeb. Active site d. products

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”)

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.

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.

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.

Optimal Catalase Activity

• 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