1. Enzyme o/a lets see what you can remember 
1. In 30 seconds, tell me 3 things you can remember about enzymes
(they are proteins, they catalyze reactions, they are specific, they can be used over and over, they lower activation energy)
2. sketch an enzyme , an active site, and a substrate and label all.

2. O/A review on enzymes continued true or false?
3. Enzymes make chemical reactions occur….
(false-they lower activation energy to make the reaction quicker/easier)
4. There are only a few type of enzymes in our bodies.
(false- since enzymes are specific, there are hundreds to thousands of them in our bodies)
5. Enzymes names are hard to understand.
(false- they are usually named be the substrate they act upon and usually end in …..ASE ex. Lipid-lipase, lactose-lactase
6. enzymes can only be used once, then they are broken down and reabsorbed.
(false- a single enzyme molecule can catalyze numerous reactions)

3. A Review of Enzymes and Chemical Reactions

4. Chemical Reactions: Chemical Reaction: Reactants: Products:
A process that changes one set of chemicals into another set of chemicals
Reactants:
Elements entered into the reaction
Products:
Elements or Compounds produced by the reaction
Always involves the breaking of bonds in reactants and forming of new bonds in products.
REACTANTS PRODUCTS

5. Carbon Dioxide in your Blood:
EXAMPLE:
Carbon dioxide plus water produces a soluble compound called carbonic acid and is carried through the blood
CO2 + H2O H2CO3
In the lungs the reaction is reversed
H2CO CO2 + H2O

6. Energy in Reactions:
Energy is either released or stored in chemical reactions…Why?
Because bonds are formed or broken!
Exothermic reactions
Reactions that release energy
Often occur spontaneously
Endothermic reactions
Absorb energy
Will not occur without a source of energy
2H2 + O H2O

7. Enzymes: Proteins that act as biological catalysts. Catalyst: Enzymes:
A substance that speeds up the rate of chemical reactions.
It lowers the activation energy required for the reaction to occur.
Enzymes:
Proteins that act as biological catalysts.
Cells use enzymes to speed up chemical reactions that take place in the cell.

8. Lock and Key Model
When you go home at night and the door is locked, can it open itself or can you use a different key
Of course NOT!
Enzymes work in the same way. Enzymes complete very specific jobs and do nothing else.
Enzymes are the specific locks
The compounds they work with are the keys!

9. Enzyme Action:
For a chemical reaction to take place, the reactants must collide with enough energy so that the existing bonds will be broken and new bonds will be formed.

11. Enzyme-Substrate Complex:
Enzymes provide a specific binding site where reactants can be brought together to react.
The reactants are known as substrates.
Substrate
Enzyme

12. The active site changes shape and forms the enzyme-substrate complex, which helps chemical bonds in the reactants to be broken and new bonds to form.
The active sites are the key holes!
The substrates are the keys!

13. Regulation of Enzyme Activity:
Enzymes can be affected by:
1. pH – can change enzymes’ shape
2. Temperature- can change enzymes’ shape and cause them not to work
3. Activators – make enzymes work faster
4. Inhibitors – slow down or stop activity

14. More Enzyme Facts
Each type of enzyme catalyzes only ONE type of reaction
Each enzyme can catalyze thousands of the same reaction every minute!

15. Naming Enzymes
The first part of the name comes from the substrate that the enzyme binds with.
Always ends in –ASE!!!
Example: Substrate = sucrose
Enzyme’s Name=sucrase

16. How do enzymes work? 1. Enzyme and a substrate are in the same area
2. The enzyme grabs onto the substrate with the active site
3. Catalysis occurs – when the substrate is changed into something new.
4. The enzyme lets go and returns to normal – the substrate is no longer the same. The substrate is now called the product