1. ENZYMES

2. Chemical Reactions
A process that changes a set of chemicals into another set of chemicals
Ex: carbon dioxide carried in the blood must first be converted to carbonic acid
Reactants = the set of chemicals that enters into a chemical reaction
Products = the set of chemicals produced by a chemical reaction
Chemical reactions break bonds in the reactants and form new bonds in the products

3. Energy
When chemical bonds break or form, energy is released or absorbed
Chemical reactions that release energy often occur spontaneously (EXOTHERMIC). Exo-exit or leave
Chemical reactions that absorb energy will not occur without a source of energy (ENDOTHERMIC). Endo=enter
Organisms need to carry out reactions that require energy
Plant get energy from sunlight
Animals get energy from plants or other animals and release energy by breaking down food

4. Energy Changes (KNOW THESE GRAPHS!!)
If the reactants have less energy than the products, energy is absorbed in the reaction
If the reactants have more energy than the products, energy is released in the reaction

5. DRAW & Label THIS!!!

6. DRAW & Label THIS!!

7. Activation Energy The energy needed to start a reaction
Energy Absorbed
Energy Released

8. THIS WILL BE ON THE TEST! Energy-Absorbing Reaction
Section 2-4
Energy-Absorbing Reaction
Energy-Releasing Reaction
Products
Activation
energy
Activation energy
Reactants
Reactants
Products
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9. Catalysts
A catalyst is a substance that speeds up the rate of a chemical reaction by lowering the activation energy.
Enzymes are proteins that act as biological catalysts to speed up chemical reactions in cells.
Enzymes are very specific and they are usually named after the reaction they catalyze and end in -ase

10. make sure you understand these concepts 2-4
Effect of Enzymes
make sure you understand these concepts 2-4
Reaction pathway
without enzyme
Activation energy
without enzyme
Reactants
Activation
energy
with enzyme
Reaction pathway
with enzyme
Products
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11. Enzyme Action
Reactants must collide with enough energy to break bonds and form new ones
Enzymes provide a site for the substrates (reactants) to react, reducing the energy needed for the reaction to occur
Enzymes are specific having an active site that is complementary to the shape of the substrates it catalyzes = “lock and key”
This forms an enzyme-substrate complex

12. Regulating Enzymes
Enzymes activity can be affected by any variable that influences a chemical reaction pH
Temperature
Ionic conditions

13. EFFECT OF TEMPERATURE ON ENZYME ACTIVITY

14. Click on the link to watch the animation

15. FITS LIKE A PUZZLE or ‘lock and key”

16. Cells have proteins that can turn enzymes “on” or “off”
Enzymes are important in regulating chemical pathways, making materials cells need, releasing energy, and transferring information