1. Enzymes

2. What is an Enzyme?
Enzyme—catalysts for chemical reactions in living things
Known as a biology catalyst
Protein that speeds up the rate of the reaction

3. Catalyst
Catalysts—a substance that decreases the activation energy needed to start a chemical reaction and increases the rate of the chemical reaction
Not changed during the chemical reaction
Activation energy—the amount of energy that needs to be absorbed for a chemical reaction to start

4. How does an enzyme work?
Each enzyme has a specific shape which causes it to bind with specific reactants
Parts of an enzyme-substrate complex:
Substrate—the specific reactants that an enzyme acts on
Active site
Enzyme

5. How does an Enzyme Work? Two methods:
Break bonds in large molecule to make smaller parts
Bind two reactants to make one product
Lock and key model
Substrates bind to an enzyme at certain places called active sites.
The enzyme brings substrates together and weakens their bonds.
The catalyzed reaction forms a product that is released from the enzyme.

6. pH or temperature will denature enzymes
What affects enzymes?
pH or temperature will denature enzymes
Changes the shape of the enzyme so it can no longer accept substrates
Will slow down or stop reactions in your body

7. Case Study: Lactose Intolerance
Deficiency in lactase
Found in small intestine to break down lactose (found in milk) to glucose and galactose
Symptoms can include abdominal cramps and nausea

8. References
Most information from Biology, McDougal Littell (2008)