1. Energy, Enzymes & Metabolism

2. Changing Matter The ability to move or change matter is called energy
Energy exists in many forms
Ex: Light & heat
Energy can be converted from one form to another

3. Changing Matter
Physical Change: When only form or shape of matter changes
Chemical Change: When one substance changes into a different substance.
Energy Laws:
Conservation of Mass
Conservation of Energy

4. Chemical Reactions Changing a substance requires a chemical reaction
During this process
Bonds between atoms are broken
New bonds are formed
A reactant is a substance that is changed in a chemical reaction
A product is a new substance that is formed

5. Chemical Reactions Reactants Products
Changes to or forms
Reactants
Products
Example: When baking soda and vinegar are combined, they erupt as carbon dioxide gas is released
NaHCO3 + CH3COOH CO2 + H2O + CH3COONa

6. Chemical Reactions
Activation Energy: The minimum amount of energy required to start a chemical reaction
Activation Energy

7. Chemical Reactions Endothermic Reactions absorb or use up heat
Exothermic Reactions give off heat

8. Biological Reactions: Enzymes
Living things carry out many chemical reactions that maintain homeostasis (stable internal environment)
Many of these reactions would not occur without help…

9. Enzymes An enzyme is a catalyst
A catalyst increases the speed and decreases the activation energy of biochemical reactions

10. Enzymes as Proteins
Most enzymes are Proteins, which are made up of amino acids
They are named for the substance they break down
Ex: Sucrase is the enzyme that breaks down sucrose
Ex: Amylase is the enzyme that breaks down amylose

11. Lock and Key Model Enzymes fit with reactants like a lock fits a key
Each enzyme has an active site (key hole) where the reaction takes place
Active site (key hole) determines which reactant/substrate (key) will fit.
Each different enzyme acts only on specific substrates
Enzymes are reusable!
Substrate
Active site
Enzyme

12. How Enzymes Work: Step 1: Substrate binds to enzyme’s active site
Chemical reaction is jumpstarted
Step 3:
Product is released

13. Controlling Enzyme Activity
Temperature and pH level
Proteins change shape as temperatures and pH levels change
Because so much of an enzyme’s activity is based on its shape, these changes can stop an enzyme from working
Inhibitors
Can slow down or stop the activity of enzymes
Ex: Snake venom; nerve gas

14. Metabolism
Our cells get most of the energy needed for metabolism from the food we eat
When food is digested, it is broken into small molecules that can enter the blood, which delivers them to the cells
THIS INVOLVES MANY ENZYMES