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.