1. Energy & Enzymes

2. Energy
All living things need a source of, and use, energy
Energy is used in series of reactions called metabolism
The amount of energy in the universe remains the same over time.

3. Law of Conservation of Energy
Energy CANNOT be created or destroyed…
…it can only CHANGE form.

4. Chemical Reactions
A process that changes one set of chemicals into another set of chemicals.
Can be
Slow Ex: Iron + Oxygen  rust
Fast Ex: Hydrogen + Oxygen  explosion

5. Chemical Reactions CO2 + H2O H2CO3 Reactants on the left
Products on the right
CO2 + H2O H2CO3

6. Vocabulary
Activation Energy: Amount of energy needed to start a reaction
Catalyst: anything that lowers the amount of activation energy needed
Unchanged or consumed during a reaction

7. Enzymes PROTEIN catalyst found in living things (biological catalysts)
HINT: Enzymes generally end in -ase (Ligase, primase, lactase)
Enzymes work as lock and key
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8. Special note on Enzymes
Enzymes are made of proteins.
They help speed up reactions and are UNCHANGED by the reaction.
Shape changes, enzyme can no longer function
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9. Enzyme Specificity
Lock and key: each enzyme is specific lock that only fits 1 key (substrate)
Substrate= reactant on which enzyme acts
Area on the enzyme to which substrate “fits” is the active site

10. How enzymes work

11. Protein Denaturation Denatured: To change a protein’s shape
Example: scrambled eggs
Recall that enzyme activity depends on shape…

12. What can denature a protein?
Change in temperature (too hot, too cold)
Change in pH

14. Chemical Reactions + Energy
Every chemical reaction involves a transfer of energy
Can be:
Exergonic: release of energy
Endergonic: absorption of energy

15. Exergonic Reaction Products have less energy than the reactants
Released as heat, light, or electricity
Examples: Glow sticks, Hot hands (Exothermic)

16. Endergonic Reaction Products have more energy than the reactants
Energy is absorbed!
Example: photosynthesis

17. Enzyme inhibition
Inhibitors: substance that prevents enzymes from working
Competitive inhibition: Competes with substrate
Noncompetitive inhibitors: Binding changes active site