Download 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 between
atoms in the reactant
molecules so they are free
to recombine in new ways
• 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
 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 protein molecules.
 Each enzyme has a unique shape with a
special area called an active site
• One or more molecules called substrates
bond to the enzyme’s active site.
• Together they form an enzyme –substrate
complex.
 An enzyme’s specific shape allows it to
fit with only one substrate like a
lock and key.
• Once the enzyme and substrate combine a
shape change occurs.
 The shape change provides the energy needed to
break or form bonds in the substrate so that
new molecules , called products, can be formed .
 They are then released from the active site.
An enzyme flick
Let the show begin....
 Enzymes are reusable – they can be used over and
over again to catalyze / speed up a specific reaction.
 Each enzyme is unique in its shape and catalytic
activity.
 Different environmental factors affect how well an
enzyme works.
 Environmental conditions that cause each type of
enzyme to work its best – Optimal condition
 pH
 Temperature
 Substrate Concentration-amount of substrate molecules
 Enzyme Concentration- amount of available enzyme
 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.

 https://www.youtube.com/watch?v=HnbNcQlzV-4
Certain conditions can cause an enzyme’s
shape to change.
If an enzyme’s shape changes it cannot
do its job. This is called denatured
Many diseases are caused by a missing or defective
enzyme.
Lactose intolerance – missing lactase______________
__________________________________________
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
• Proteases –
break proteins to
amino acids
• Lipases –
break lipids to fatty
acids
• Nucleases – break
nucleic acids DNA
and RNA to
nucleotides
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.