1. Chemistry of Living Things
Enzymes
Chemistry of Living Things

2. What are we learning? Benchmark: Objectives:
I will explain the role of enzymes as catalysts
SC.912.L – Explain the role of enzymes as catalysts that lower the activation energy of biochemical reactions. Identify factors, such as pH and temperature, and their effect on enzyme activity. AA

3. What is a catalyst?
The activation energy (Ea) is the energy needed to start a chemical reaction.
A catalyst is a substance that increases the rate of a chemical reaction by lowering the activation energy.
Catalyst are not used up in the chemical reaction. What is a result of this?

4. What are enzymes?
Enzymes are special PROTEINS that act as biological catalysts by speeding up chemical reactions that take place in cells.
The reactants in enzyme-catalyzed reactions are know as substrates.
Substrates bind to a part of the enzyme called the active site.
The shape of the active site is complementary to the shape of the substrates.
“lock and key” model
Makes the shape of the protein very important and any change in the amino acid sequence or unfolding of the protein can make the enzyme nonfunctional

5. Enzyme Reaction Lab

6. Enzymes are biological catalysts that change the rate of a chemical reaction. For example,
2H2O2  2H2O + O2. This reaction occurs because all living tissues contain the enzyme catalase. Hydrogen peroxide is a harmful by-product of cellular respiration. Cells use enzymes to break down poisonous chemicals very rapidly to prevent a buildup of lethal amounts.

7. Factors that affect Enzymes
Enzymes can be affected by changes in temperature, pH, and concentration of enzyme and substrate molecules.
Temperature
Lower enzyme works slower
Higher enzyme works faster
Extreme (boiling, Fever) the enzyme will denature (the protein loses its shape) pH
At a higher or lower than normal pH, enzyme will not function because it becomes denatured (the protein loses its shape)
Concentration
Substrate
Higher substrate concentration enzyme will work faster
Lower substrate concentration enzyme will work slower
Enzyme
Higher enzyme concentration, reaction is faster
Lower enzyme concentration, reaction is slower

8. Why might an enzyme function incorrectly if its shape were changed?
Essential Question
Why might an enzyme function incorrectly if its shape were changed?
An enzyme and the molecule with which it reacts must fit together. Changing the shape of a protein would prevent it from fitting and thus would affect the function of that protein.