1. 2.4 Chemical Reactions and Enzymes

2. Chemical Reactions What is a chemical reaction?
A process that changes one set of chemicals into another
Some bonds are broken and new bonds are formed

3. Chemical reactions and energy
Some release energy
Gets hot
Ex: the foam experiment
Some use energy
Gets cold
Ex: instant ice pack
Some reactions are fast
Some reactions are slow

4. Why should we care about chemical reactions??
Our bodies need them to happen inside of us to survive.
(so do all living things)

5. Chemical reaction in the lungs
A chemical reaction allows you to get rid of carbon dioxide from your blood so you can breathe it out.

6. Chemical reaction in your mouth!
Chemicals in your saliva help you to start breaking down starch in your food.

7. Chemical reactions in your stomach
Chemical reactions in your stomach help you to break down food to get energy

8. Many chemical reactions need ENERGY, and they won’t just happen on their own!!!
In order to stay alive, organisms need energy to carry out reactions inside of them.
The amount of energy needed to get a chemical reaction started is called “activation energy”
Ex: lighting paper on fire.

9. Many reactions need a lot of activation energy
If you had to use a ton of activation energy for every single reaction in your body, your body would never get anything done.

10. We need a helper…

11. What can we use INSTEAD of a ton of activation energy?
Enzymes.
Enzymes are proteins that speed up chemical reactions so that you don’t need a ton of activation energy.
Aka “catalysts”

12. How an enzyme works
Normally, reactants would have to find each other and hit each other with a bunch of energy in order to react.
Enzymes have a specific spot on them where they can bring reactants together to react, so that doesn’t have to happen
Enzymes weaken the bonds of reactants, too.

13. The reactants in a reaction sped up by catalysts are called substrates.
Catalysts and substrates bind together like a lock and key

14. Enzymes are particular
They require specific temperature, pH, and other molecules to work properly.

15. Enzymes video http://www.youtube.com/watch?v=3UsCRN6DM3Y
pilot video