Objectives

• Differentiate between reactants and products in a chemical reaction.

• Describe the process of the chemical reaction and explain how enzymes catalyze chemical reactions by lowering the activation energy.

• Recognize that enzymes are specific and are not used up in a chemical reaction.

• Create analogies that demonstrate understanding of the role of enzymes.

Chemical Reaction

Reactants

ProductsActivation Energy

ENZYME

Catalyst

Substrate Active Site

Induced Fit

ENZYME

• Biological Catalyst• Catalyst = speeds up the

rate of chemical reaction by LOWERING activation energy.

• Substrate or Reactants bind to active site.

• Makes reactions happen FASTER

Active SiteActive Site

A restricted regionrestricted region of an enzymeenzyme molecule which bindsbinds to the substratesubstrate.

Chemical Reactions• Recipe Ingredients are to

Cake as Reactants are to Product

• Reactants or Substrate are the starting substances.

• Chemical reactions allow living things to grow, develop, reproduce and adapt.

• New Products are made as atoms are rearranged.

Chemical Reactions

• Reactants Products

• C6H12O6 + O2 CO2 + H20

• Just like cake is made with flour, sugar, and other ingredients mixed together, it is not cake until you bake it.

• The key to starting a chemical reaction is energy.

yieldsyields

yieldsyields

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So How Do So How Do EnzymesEnzymes Work? Work?

Enzymes work by weakening weakening bondsbonds which which lowers lowers activation activation energyenergy

Activation Energy = minimum amount of energy needed for reactants (substrate) to form Products (new substance)

EnzymesEnzymes

FreeEnergy

Progress of the reaction

Reactants

Products

Activation EnergyActivation Energy

Without EnzymeWith Enzyme

Lowers ActivationEnergy

9

EnzymeEnzyme--SubstrateSubstrate Complex Complex

The substancesubstance (reactant) an enzymeenzyme acts on is the substratesubstrate

EnzymeSubstrateBinds to Active Site

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Induced FitInduced Fit• A change in the shapeshape of an enzyme’s active site• Induced Induced by the substrate

Examples of Enzymes at Work

• Notice simple to more complex drawings.• Each illustrates how an enzyme works.• See if you can identify Enzyme, Reactants

(Substrate), Products, active site, and induced fit.

• Remember the job of the enzyme is to LOWER the activation energy so the chemical reaction works FASTER.

Reactants (Substrate)

Enzyme ChemicalReaction

Products

Enzyme

Notice Reactants (Substrate bind to enzyme where chemical reaction occurs faster because the activation energy is lowered (less energy needed than without enzyme). The enzyme is ready to act again and does NOT become part of the Products.

Active Site

Reactants/Substrate Products

Notice Name of Enzyme

NoticeName ofSubstrate

Name of Enzyme ends with “ASE” and is named according to its job.

Enzymes

• Have a specific job • Do NOT get used up or become part of

product.• Lowers the activation energy needed to get

the reaction started.• Makes the reaction happen faster.

Can you finish these analogies about Enzymes and create your own?

• An enzyme is to a reaction, as a ____ is to a lock.

• Ose is to a carbohydrate as ____ is to an enzyme.

• Ingredients are to a cake, as _________ are to the Product.

key

Ase

Reactants

Review Key Vocabulary and

Relate to ENZYMES

Chemical Reaction

Reactants

ProductsActivation Energy

ENZYME

Catalyst

Substrate Active Site

Induced Fit

Proceed to Quiz or Review PowerPoint