Section 2.5 Enzymes

Word Splash

• Enzyme Active Site

• Biological Catalyst Activation Energy

• Substrate Denatured

• Lock and Key Reusable

Key Concept

• Enzymes are proteins that speed up chemical rxns in living cells by lowering the amount of activation energy (EA) needed to get them started

Chemical Reactions require E

• Energy is needed to start a chemical reaction.

• This energy is used to

break the bonds within the reactant molecules

• The amount of energy needed is called activation energy (Ea).

Function of Enzymes

• Enzymes make rxns go faster by

reducing the amount of activation energy

needed for the reaction to start

What’s needed to get the rock rolling down the hill on its own? ENERGY INPUT

Activation Energy

A catalyst speeds up the rate of the reaction by reducing the amount of activation energy needed to start the reaction.

Because enzymes have the job of catalysts in living things they’re called biological catalysts.

Enzymes are Biological Catalysts

Enzymes are protein molecules.

How Enzymes Work

Each enzyme has a unique shape with a special area called an active site

Enzyme Shape determines Function

Enzyme – Substrate Complex• One or more molecules called

substrates bond to the enzyme’s active site.

• Together they form an enzyme –substrate complex.

Lock and Key TheoryAn enzyme’s specific shape allows it to fit with only one substrate like a

lock and key.

Enzyme – Substrate Complex• Once the enzyme and substrate

combine a shape change occurs.

The shape change provides the energy needed to caused bonds in the substrate to break or form resulting in new molecules , called products, being formed .

They are then released from the active site.

Enzymes help reactions go faster

An enzyme flick

Let the show begin....

EnzymesEnzymes are reusable – they can be used

over and over again to _______________ a specific reaction.

Each enzyme is unique in its shape and catalytic activity.

Different environmental factors affect how quickly an enzyme can speed up a reaction.

There are certain environmental conditions that cause each type of enzyme to work its best – Optimal condition

Enzymes are Unique

pH

Temperature

Substrate Concentration-amount of substrate molecules

Enzyme Concentration- amount of available enzyme

Factors that Affect Enzyme Activity

The environmental conditions that cause each type of enzyme to work its best are called – optimal level.

For example, 98.6 ° is the optimal temperature for enzymes to work in the human body.

Optimal Conditions

Enzyme Activity Graphs

https://www.youtube.com/watch?v=HnbNcQlzV-4

Affect of Substrate Concentration

Certain conditions can change an enzyme’s shape which makes it unusable.

Denature – change a molecule’s shape

Enzymes can be Denatured

Many diseases are caused by a missing or defective enzyme. Lactose intolerance – missing ______________ __________________________________________ Phenylketonuria (PKU) – missing phenylketonurase. __________________________________________

Enzyme Activity Graph with zones of activity/inactivity

Quick Facts about Enzymes

• Enzymes are protein molecules

• Enzymes function to make reactions

go faster

• Are reusable

• There are about 2000 different enzymes in each one of your cells

• Each enzyme fits with only ________ substrate molecule

• Names usually end in -ase

General Types of Enzymes

• Amylases –

break starch to glucose

• Lipases –

break lipids to fatty acids

• Proteases –

break proteins to

amino acids

• Nucleases – break nucleic acids DNA and RNA to nucleotides

Factors that affect Enzyme Action

How do enzymes work?• Each enzyme has a unique 3-D shape, including a surface

groove called an ACTIVE SITE.

• One or more molecules called SUBSTRATES chemically bond to the enzyme’s active site.

• When joined they are called an ENZYME-SUBSTRATE COMPLEX

• Changes in how the atoms are bonded occur resulting in new molecules being made called PRODUCTS .

• Products are then released from the active site.