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EnzymesEnzymes

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What Are Enzymes?What Are Enzymes?• Most enzymes

are ProteinsProteins• Enzymes act as a

catalystcatalyst to speed up speed up (catalyzecatalyze) a chemical reaction

• Enzymes are Enzymes are not not permanently permanently changedchanged in the process of a chemical reaction.

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3 Big Ideas3 Big Ideas1. Enzymes are

specific for what they catalyze.

2. Enzymes are reuseable..

3. Enzymes end in - ase- amylase- protease- lipase- lactase

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How do enzymes Work?How do enzymes Work?

Enzymes lower the lower the amount of energy amount of energy the reaction needs.

This energy is called activation activation energy energy because is activates the reaction.

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EnzymesEnzymes

FreeEnergy

Progress of the reaction

Reactants

Products

Free energy of activationFree energy of activation

Without Enzyme

With Enzyme

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Binding to the EnzymeBinding to the EnzymeThe enzymeenzyme

reacts with the substrate.substrate.

EnzymeSubstrate Joins

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Binding to the EnzymeBinding to the Enzyme• The active site active site of an enzyme

molecule is where the substrate binds to the enzyme.

EnzymeSubstrate

Active Site

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What Affects Enzyme Activity?What Affects Enzyme Activity?

• Three things:Three things:

1.1. Environmental ConditionsEnvironmental Conditions

2.2. Cofactors and CoenzymesCofactors and Coenzymes

3.3. Enzyme InhibitorsEnzyme Inhibitors

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1. Environmental Conditions1. Environmental Conditions 1. Extreme1. Extreme Temperature Temperature are the are the

most dangerousmost dangerous

- - high temperature may denature denature (unfold) (unfold) the enzyme. enzyme.

2.2. pHpH (most like 6 - 8 pH near (most like 6 - 8 pH near neutral)neutral)

3.3. Ions Ions in a solution (like salt)in a solution (like salt)

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2. Cofactors2. Cofactors

• Cofactors are other Cofactors are other molecules molecules that that have to attach to the enzyme for it have to attach to the enzyme for it to work.to work.

• Example:Example:IronIron must be present in the enzyme enzyme

hemoglobin hemoglobin in order for it to pick up oxygen.

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3. Enzyme Inhibitors3. Enzyme Inhibitors

Competitive inhibitors Competitive inhibitors compete with the substrate compete with the substrate byby blocking the active site. blocking the active site.

Enzyme

Competitive inhibitor

Substrate

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InhibitorsInhibitors

Noncompetitive inhibitorsNoncompetitive inhibitors::Inhibitors that bind tobind to another another

partpart of the enzymeenzyme and force the force the active site to close active site to close so that the substrate doesn’t fit.

Enzymeactive site altered

NoncompetitiveInhibitor

Substrate

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Review Questions

1. Which type of biomolecule is an enzyme?

2. What do enzymes do to reactions?

3. What is the name of the thing that binds with the enzyme?

4. What are the three factors that can affect enzyme activity?

5. What are the two types of enzyme inhibitors and how do they work?

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Cell Organelles Review

What does it look like and what does it do?

Nucleus Mitochondria Ribosomes

Golgi Apparatus ChloroplastsCentrioles

Lysosome Endoplasmic Reticulum(smooth and rough)

Cell Wall Central VacuoleMembrane

(Nucleolus PlasmodesmataVesicles)

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Example: Muscle Movement

Our muscles move by the interaction of 2 proteins known as actin and myosin.

1.The actin have active sites which bind with the myosin to contract the muscle.2.The binding sites on the actin are block by tropomyosin, a filament that keeps the actin from reacting with the myosin when we are not using our muscles.3.Calcium ions bind to the troponin complex on the tropomyosin protein and change its shape.4.The shape-change causes it to rotate and expose the actin active sites, which then bind with myosin.

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