1. BELLRINGER
 What were the 2 food-based chemical
reactions we studied in yesterday’s
experiment?
 What are the proteins that speed up metabolic
reactions called?

2. AGENDA
 Collect LAB: Exploring Enzymes
 NOTES: Enzymes
 Shape, Function, and Naming
 Factor’s that slow enzymes
 Activation Energy

3. ENZYMES & SUBSTRATES
 Enzymes are proteins that catalyze (speed
up) chemical reactions in the body
 The molecules that are affected by enzymes
are called substrates
 Example: Amylase is an enzyme in saliva
that breaks down starchy foods like bread
and pasta. In this case, starch is the
substrate of amylase.

5. SUMMARY OF ENZYME PROPERTIES
 Shape: Enzymes are globular (balled up) proteins
 Function: Enzymes work by temporarily bonding with
substrate molecules
 Reusable: A single enzyme can be used multiple times
 Name: Enzymes are named for the substrates they
affect

6. SHAPE OF ENZYMES
 Enzymes are long protein chains that are “knotted up”
like a ball of yarn.
 The surface of an enzyme has a small pocket called
the active site which is shaped to bind substrate
molecules.
Enzyme
Active Site
Substrate

8. HOW ENZYMES WORK
 Substrate molecules temporarily bond with the
enzyme at the active site.
 The enzyme bends the substrate in a way that
either breaks the molecule apart or allows it to
bond with another substrate
 Once the reaction is complete the enzyme
releases the products.

9. SUMMARIZE WHAT IS HAPPENING IN THE VIDEO
CLIP . . .

10. ENZYMES ARE REUSABLE
 An enzyme only bonds with the substrate it
works on for a short time.
 After the reaction is over, the enzyme returns
to it’s original shape and is ready to work
again.
 A single enzyme can induce millions of
reactions per second.

11. ENZYMATIC REACTION
substrate (sucrose) + enzyme (sucrase) 
enzyme-substrate complex 
and +
sucrase
glucose fructose
products + enzyme

12. ENZYME NAMING
 Enzymes are specific to only one substrate.
 Since each enzymes only works on one
reaction, they are named for the molecules they
affect.
 To name an enzyme, simply add the ~ase
ending.
 Examples
 Lactose sugar is broken down by the enzyme
Lactase

13. FACTORS THAT SLOW ENZYMES
 Enzymes are only effective when their active
site is in the proper shape.
 Since enzymes are proteins, they can
become denatured (unfolded) and will no
longer work.
 2 things will denature proteins
 Changes in pH
 Changes in Temperature

15. ACTIVATION ENERGY
 Many chemical reactions need energy to begin.
 This energy that starts a reaction is called the
activation energy.
 Examples:
 Photosynthesis requires activation energy from the
sun
 Wood will not start burning without initial heat
source

17. ACTIVATION ENERGY VIDEO CLIP

18. ENZYMES LOWER ACTIVATION ENERGY
 Enzymes speed reactions up by reducing the
amount of activation energy a reaction
needs.
 The activation energy is reduced because
the molecules at the active site are held in
positions that make reactions easier.