1. Chapter 2, Section 4
Chemical Reactions & Enzymes
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2. Metabolism
Combination of all chemical reactions necessary for maintaining life.
Chemical reactions change molecules into new ones by:

3. Activation Energy Energy required to start a chemical reaction
Amount depends on type of chemical reaction

4. How to Increase Chemical Reaction Speeds?
Increasing temperature causes molecules to move around faster
PROBLEM: biological systems are sensitive to temperature changes
SOLUTION: enzymes are biological catalysts without changing the system’s temperature

5. What Are Enzymes?
Enzymes are proteins that speed up chemical reactions
Decrease activation energy
Creates new reaction pathway

6. How Do Enzymes Work? Substrate(s)/reactants enter the active site
Known as induced fit OR “Lock and key” model
Lowers activation energy
Bringing reactant molecules close together
Placing stress on bonds that need to be broken
Products released from active site
Enzyme reverts to original shape and can receive another substrate

8. Enzyme Reaction Rates Measured in the formation of products over time
Rate = (Y2-Y1)/(X2-X1)
Factors that impact an enzyme’s reaction rate
Substrate concentration
Competitive inhibitor pH
Temperature

9. Substrate Concentration
Reaction rate will increase as substrate rate increases until it hits its saturation point
Point when all enzymes are being used

10. Competitive Inhibitor
Molecule with a similar shape as substrate block active site on enzyme
Decreasing enzyme reaction rate

11. Enzyme’s Shape Role in Reaction Rate
Recall that all proteins have a highly specific 3D shape that they fold into
They are ONLY able to function while in this shape
The specific shape of the protein determines the shape of the active site
All enzymes function within a narrow range of optimal pH and temperature
pH and temperature outside of the optimal range can cause enzyme denaturation (change in shape)
Enzyme denatures, is unable to bind substrate
Reaction rate slows/eventually stops

12. pH Denaturation can occur outside of optimum levels
Different types of enzymes have different optimum pH levels
Denaturation can occur outside of optimum levels

13. Temperature
As temperature increases, enzyme reaction rate increases UNTIL it passes the optimal range
Denaturation happens after max temperature