1. KEY CONCEPT Enzymes are Protein Catalysts

2. A catalyst lowers activation energy.
Catalysts are substances that speed up chemical reactions in 2 ways:
decrease activation energy needed to start the reaction
increase the speed of the reaction

3. A catalyst lowers activation energy.
Chemical reactions have 2 sides:
Reactants > Products
“hydrogen peroxide yields water and oxygen gas”
H2O > H2O + O2

4. HW: BioChem Review – Due Thurs. 10/31 Test Packet – Due Friday 11/1
First Five 10/29
Do you think enzymes can ever run out? Why or why not?
Schedule
First Five
Notes enzymes
Play dough demo
HW: BioChem Review – Due Thurs. 10/31
Test Packet – Due Friday 11/1
Catalase lab – Due Friday
GQ: How do enzymes work?

5. Enzymes allow chemical reactions to occur safely and rapidly in all living cells.
Examples:
Enzyme names: What it speeds up:
Lactase breaks down lactose (a sugar)
Amylase breaks down amylose (a starch)
Peptidase breaks down polypeptides (proteins)

6. Remember-
-An enzyme’s function depends on its protein structure.
-Changes in temperature and pH can denature enzymes.
-When its shape is lost it loses the active sites and it can’t work.

7. Enzyme structure fits a specific molecule the way a key fits a specific lock.

8. 1. The lock-and-key model shows an enzyme making a bigger molecule.
substrates brought together at the active sites
bonds in substrates weaken, new bonds form in product.
Substrates bind to an enzyme at certain places called active sites.
The enzyme brings substrates together and weakens their bonds.
The catalyzed reaction forms a product that is released from the enzyme.
Enzyme/substrate complex

9. 2. Induced Fit Model of an Enzyme that catalyzes reactions to split larger molecules into smaller molecules.
Enzyme changes shape slightly to fit the substrate as it binds at active sites.
Bonds break in the substrate and products are released.

10. Induced Fit Enzyme Model for Monday’s Lab
H2O > H2O + O2
Catalase enzyme puts stress on H2O2 so less energy is needed to break its bonds.

11. Pineapple and Gelatin