1. Chemical Reactions and Enzymes

2. Objectives Identify the parts of a chemical reaction.
Relate energy changes to chemical reactions.
interpret energy diagrams
Summarize the importance of enzymes in living things.
enzymes (definition)
“lock and key” model
effect of temp. and pH on enzyme activity
effect of concentration on enzyme activity

3. Chemical Reactions Definition Chemical bonds are broken and/or formed.
process by which atoms or groups of atoms in substances are reorganized into different substances
Chemical bonds are broken and/or formed.

4. Chemical Equations Reactants Products Read the following: “yields”
C6H12O6 + 6O2 --> 6H20 + 6CO2
glucose oxygen water carbon dioxide
“yields”

5. Energy of Reactions Energy Activation Energy (Ea) Energy Change ( H)
needed to start chemical reactions
Activation Energy (Ea)
minimum amount of energy needed for reactants to form products
Energy Change ( H)
(Energy of Reactants - Energy of Products)
Exothermic ( H)
energy of products lower than energy of reactants
Endothermic (+ H)
energy of products higher than energy of reactants

6. Energy Diagram Exothermic Reaction
Peak represents the amount of energy that must be added to the system to make the reaction go

7. Energy Diagram
Endothermic

8. ___________ HELP CHEMICAL REACTIONS _______________
Catalysts
___________ HELP CHEMICAL REACTIONS _______________
CATALYSTS
HAPPEN FASTER
Catalysts work by ____________ the
___________________________to get a chemical reaction started.
DECREASING
ACTIVATION ENERGY required
NOTE:
does not increase the amount of product
does not get used up in the reaction

9. Enzymes Enzymes types of proteins act as biological catalysts
speed up the rate of reaction in biological processes (by lowering activation energy)
most are specific to one reaction

10. Enzymes Naming Enzymes Examples: many end in _____
beginning of the name tells what it does
Examples:
DNA Polymerase
“polymerizes”
joins monomers to make DNA
Protease
breaks down proteins
ATP synthase
synthesizes ATP

11. Energy Diagram

12. Enzymes Substrate Active Site
reactants that bind to the enzyme
Active Site
location where the substrate binds on the enzyme
Enzymes combine with the substrate in the active site to form the enzyme-substrate complex

13. Enzymes Lock & Key Model: Enzymes exhibit specificity:
substrate and active site -> complimentary shapes (puzzle pieces that fit together)
Enzymes exhibit specificity:
enzymes only fit with a particular substrate
due to the shape of the active site

14. 3) Enzyme-Substrate Complex
Enzyme Demonstration
5) Product Released; enzyme free to react again
1) Substrate
2) Fits into active site
4) Reaction takes place
3) Enzyme-Substrate Complex

15. Enzymes Factors that affect enzyme activity pH temperature
concentration (amt.) of substrate
concentration (amt.) of enzyme

16. Enzymes Optimal pH (dependent on enzyme)
Too low -> decreased rate of reaction
Too high -> enzyme denatures (breaks apart)

17. Denatured Proteins
When a protein loses its shape (its tertiary (3-D) structure)
Cause:
-high temperature (like on the stove)
-pH extremes (like in your stomach)
Effect:
-Losses its ability to function
-Properties can change
(become insoluble, change color)
Happens when a protein loses its structural integrity, its tertiary (3-D) structure is destroyed

18. Denatured Proteins changes shape ACTIVE SITE CAN’T BIND
Denaturing an enzyme _______ the _______ of the ______________ so enzyme ______________ to ____________
shape
ACTIVE SITE
CAN’T BIND
SUBSTRATE
As a result, the reaction occurs at a reduced rate or stops all together.

19. Denatured Proteins
As a result, the reaction occurs at a reduced rate or stops all together.

20. Enzymes Optimal Temp. Temp , Activity
Temp too high-> protein denatures (breaks apart)

21. Enzymes Predict what would happen if…
(1) you added more enzyme to the reaction?
(2) you added more substrate to the reaction?
what if you added more enzyme to the reaction?
what if you added more substrate to the reaction?

22. WHITEBOARDS!
How does the amount of the substrate and the amount of enzyme affect the rate of reaction?

23. Lab: Understanding Enzymes
Objectives:
Understand the function of enzymes in the human body.
Observe the function of several commercially important enzymes.
Predict the effect of enzyme concentration, temperature, and pH on enzyme activity rate.
Understand the structure of enzymes & how denaturation occurs.
Graph enzyme activity rates and different enzyme concentrations.

24. Enzyme Inhibitors Competitive Inhibition Non-Competitive Inhibition
plug up active site-->substrate can’t bind
Non-Competitive Inhibition
bind to enzyme (not in active site) --> change shape of active site

25. Enzyme Inhibitors May be Examples Permanent - covalent bond
Reversible - hydrogen bond
Examples
Nerve gas
Penicillin
Cyanide
Aspirin
AZT

26. Online Tutorials for additional information & visuals
Note: Not required.

27. Can you… …identify the parts of a chemical reaction?
…relate energy changes to chemical reactions?
interpret energy diagrams?
…summarize the importance of enzymes in living things?
enzymes (definition)?
“lock and key” model?
effect of temp. and pH on enzyme activity?