1. Learning Objectives
Define the following terms: enzyme, chemical reaction, reactant, product, activation energy, catalyst, enzyme-substrate complex.
Describe how a catalyst will affect the activation energy.

2. Enzymes and Chemical Reactions

3. Chemical Reactions CO2 + H2O H2CO3
A chemical reaction is a process that changes or transforms one set of chemicals into another.
CO2 + H2O H2CO3
Carbon Water Carbonic acid
Dioxide
Reactants Product

4. Reactants
O2 + 2H H2O
Reactants - elements or compounds that enter into a chemical reaction.

5. Products
O2 + 2H H2O
Products - elements or compounds produced by a chemical reaction.

6. Chemical Reactions CO2 + H2O H2CO3
Carbon Water Carbonic acid
Dioxide
Chemical reactions always involve changes in the chemical bonds that join atoms in compounds. These reactions require energy.

7. Activation Energy
Energy
Activation
Energy
Reactants
Products
Course of Reaction
Activation energy - the amount of energy required for a chemical reaction to get started.

8. Stop Here

9. Activation Energy
Products
Activation energy - the amount of energy required for a reaction to get started.

10. Enzymes
A catalyst is a substance that speeds up the rate of a chemical reaction. Catalysts lower the activation energy.

11. Enzymes are specific
Reactant
(substrate)
Enzyme
Enzymes are proteins that act as biological catalysts. Enzymes are very specific, generally catalyzing only one chemical reaction.

12. Enzyme-Substrate Complex
Substrates - reactants of enzyme-catalyzed reactions
substrate
Enzyme-
Substrate
Complex
Products
Chemical
Reaction
Enzymes provide a site where reactants can get together to complete a chemical reaction, thus reducing the activation energy.

13. Enzymes
Enzymes lower the energy needed (activation energy) and speed up the chemical reaction.

15. Enzymes can be reused over and over again!

16. Function of Enzymes Regulating chemical pathways
Making materials that cells need
Releasing energy
Transferring information

17. Regulation of Enzyme Activity
Denatured Enzyme pH
Temp
Ionic strength
Solubility
The active site of the enzyme changes shape and can no longer bind to the substrate