Post on 18-Jan-2016
ENZYMES and Activation Energy
EQ: How do enzymes affect a reaction
What is Energy?• Energy is the ability to cause
matter to move or change.
• All life processes are driven by energy
• Where does all energy come from?
Chemical Reactions• When bonds are broken and
reformed to make different substances, energy is released.
EX:
Reactants Products
C6H12O6 + 6O2 6CO2 + 6H2O
What is Metabolism?• Metabolism is the sum of all
chemical reactions in your body
- Metabolism is basically two components
1. Breaking down foods for energy
2. Building new compounds to make you
What is needed to start a reaction?
En
ergy
ab
sorb
ed
Act
ivat
ion
en
ergy
reactant
ProductsEnergy released
Activation Energy isthe energy needed tobreak down reactants
into products.
What is a Catalyst?• A catalyst is anything that lowers
activation energy.
• Enzymes are organic catalysts.
•Predict what the graph will look like after a catalyst (enzyme) is added.
What do you notice about the activation energy?
En
ergy
ab
sorb
edE
ner
gy r
elea
sed reactant
Products
Activation energy
En
erg
y a
bs
orb
edE
ner
gy
re
lea
sed
Reactant
Products
Comparing Reactions Which line would represent a reaction without an enzyme present?
With an enzyme present?
Enzymes lower the amount of activation
energy needed
How Do Enzymes Work?• Enzymes work
like a lock and key.
• Specific enzymes have an ACTIVE SITE for specific substrates.
enzyme
substrate
How Do Enzymes Work?1. Each substrate fits into the
enzyme’s active site.
2. Then the enzyme controls the rate of the chemical reaction.
3. The substrate is broken into products.
4. The enzyme is free to accept another substrate.
Enzymes are NEVER used up in a reaction!! the reaction rate is
controlled by enzymes
Demo Time!!1. Find your 2:00 clock buddy.
2. Pair up with another set of clock buddies (optional).
3. Develop a short play or demonstration that illustrates
how enzymes catalyze reactions.
Inhibitors Competitive
Inhibition
Occurs when a molecule mimics the substrate and enters the active site, not allowing the real substrate to fit.
Non-competitive Inhibition
Occurs when a molecule binds to an enzyme somehwere other than the active site, causing a change in shape.
Enzymes can be affected by:
• Temperature:
• pH:
• Concentration:
0 3 75 9 11 13
Neutral
Battery Acid
BleachBlood (7.5)
Denaturation A protein is denatured when it
loses its shape and becomes inactive.
Demo Time!!1. Find your 2:00 clock buddy.
2. Pair up with another set of clock buddies (optional).
3. Modify your demonstration to include competitive and non-
competitive inhibitors.