1. Welcome Back! Do Now Turn in Lab 04 Answer: What is pH?
What is an acid?
What is a base?
What is the range of the pH scale?
If I have a solution that has a pH of 7, is it an acid, base, or neutral?
What is the neutral solution that we learned?

2. A little background information.
Before we begin…
A little background information.

3. Chemical Reactions
A chemical reaction is a process that changes one set of chemicals into another set of chemicals
Reactants: elements or compounds that enter into a chemical reaction
Products: elements or compounds produced by a reaction
Activation Energy: the energy that is needed to start a reaction

4. Activation Energy Some reactions occur quickly…
Other chemical reactions occur slowly….
H gas ignited in the presence of O = rapid and explosive reaction
Such as the combination of iron and oxygen to form an iron oxide called rust

5. What helps speed up these reactions…?
Activation Energy
Some chemical reactions that make life possible are too slow or have activation energies that are too high to make them practical for living tissue
What helps speed up these reactions…?

6. Can you name a catalyst that we learned…?
Catalysts!
Cells make catalysts to make certain chemical reactions possible!
Catalyst: a substance that speeds up the rate of chemical reaction
Works by lowering a reaction’s activation energy.
Can you name a catalyst that we learned…?

7. Enzymes

8. What Are Enzymes? All enzymes are made from proteins
Enzymes are catalysts - accelerate a reaction
Structure is not changed in the process

9. Enzymes Are specific for their substrate Are Reusable End in –ase
Substrate: reactants of an enzyme-catalyzed reaction
Are Reusable
End in –ase
-Sucrase, lactase, maltase
Catalyze = to break down; digestion
Synthesize = start with 2 to make 1
Similar to reactant and product, you have substrate and product

10. How do enzymes Work?
Enzymes work by weakening bonds which lowers activation energy
Animation

12. A Lock and Key! It’s Something like…
shape of protein allows enzyme & substrate to fit
specific enzyme for each specific reaction

13. Activity
Enzyme Cut out

14. Welcome Back! Do Now Turn in homework! Answer:
What is activation energy?
What are catalysts?
What are enzymes?
What is the enzyme-substrate complex?
What does the “lock and key” analogy mean?
Lock & Key
shape of protein allows enzyme & substrate to fit
specific enzyme for each specific reaction

15. Re-Loop: Enzyme-Substrate Complex

16. Enzyme-Substrate Complex
Joins
Substrate: the substance (reactant) an enzyme acts on

17. Enzyme-Substrate Complex
Active Site
Enzyme
Substrate
Active Site: a restricted region of an enzyme molecule which binds to the substrate.

18. What Affects Enzyme Activity?
Three factors:
Environmental Conditions pH
Enzyme Inhibitors

19. 1. Environmental Conditions
Extreme Temperature are the most dangerous
- high temps may denature (unfold) the enzyme.
pH (most like pH near neutral)
Ionic concentration (salt ions)

20. 1. Environmental Conditions
Effect on rates of enzyme activity
Optimum temperature
greatest number of collisions between enzyme & substrate
human enzymes = C (body temp = 37C)
Raise temperature
denature protein = unfold = lose shape
Lower temperature
molecules move slower
decrease collisions

21. Effect on rates of enzyme activity
2. pH
Effect on rates of enzyme activity
pH changes protein shape
most human enzymes = pH 6-8
depends on where in body
pepsin (stomach) = pH 3
trypsin (small intestines) = pH 8

22. Competitive inhibitors
3. Enzyme Inhibitors
3 Inhibitors:
Competitive inhibitors
Substrate and a substance resembling the substrate are both added to the enzyme.
Enzyme
Substrate
Competitive inhibitor

23. 2. Noncompetitive inhibitors:
3.Enzyme Inhibitors
2. Noncompetitive inhibitors:
Molecule binds to an enzyme somewhere other than the active site.
 molecule binds to an enzyme somewhere other than the active site. This changes the enzyme's three-dimensional structure so that its active site can still bind substrate with the usual affinity, but is no longer in the optimal arrangement to stabilize the transition state and catalyze the reation.
Enzyme
Noncompetitive
Inhibitor
Substrate
active site
altered

24. Excessive amounts of substrate are present
3.Enzyme Inhibitors
3. Substrate Inhibition
Excessive amounts of substrate are present
Enzyme
Substrate
Substrate
Substrate
Substrate

25. Murder And A Meal: The Case
Lab 05

26. Welcome Back! Do Now Turn in lab 5! Answer:
What is the enzyme-substrate complex?
What does the “lock and key” analogy mean?
What happens if enzymes encounter extreme temperatures?
What is the pH of most enzymes?
Name the three enzyme inhibitors
Lock & Key
shape of protein allows enzyme & substrate to fit
specific enzyme for each specific reaction

27. Agenda
Do Now
Group Test Review
Review Scavenger Hunt
Test = FRIDAY

28. Welcome Back! Do Now Get ready for your test! Answer:
How do you feel about this class so far? What improvements can Ms. Fields make to make this class better for you.
Lock & Key
shape of protein allows enzyme & substrate to fit
specific enzyme for each specific reaction

29. It’s almost test time…
Quick Review

30. Review topics Organic, inorganic Carbohydrates – monomers and polymers
Monosaccharides
Glucose, galactose, fructose
Starch = energy in plants
Cellulose = structure in plants
Proteins
When ingested by animals = amino acids
Chemical indicators
Brown bags, Benedict’s, Iodine, Biuret

31. Review topics Hydrolysis Dehydration Synthesis
Addition of water to break polymers into monomers
Dehydration Synthesis
Removing water to make monomers into polymers
Enzymes – put together (synthesize) or break apart (decompose) substances; speed up reactions
Catalase
Are chemically specific (they only work with the particular substrate)
Denaturing
STERNGRR