1. IV. pH H2O H+ + OH- A. Dissociation of Water Molecules:
1. Water molecules split to form ions.
(hydroxide ion)
H2O H+ +
OH-

2. *The dissociation of water is reversible.+
OH-
H2O

3. 2. In pure water, H+ and OH- are equal in concentration.
3. Certain substances can cause imbalances in these concentrations.
a. These substances are called ACIDS and BASES.

4. B. Acids 1. Add (donate) more H+ when dissolved in water.
2. More H+ = stronger acid
3. Taste sour
Example: HCl  H+ and Cl-

6. C. Bases 1. Add more OH- when dissolved in water.
2. More OH- = stronger base
3. Alkaline
4. Taste bitter
Example: NaOH  Na+ and OH-

8. The measure of how acidic or basic a compound is
D. pH scale
The measure of how acidic or basic a compound is
Neutral 7
strong
weak
weak
strong
Basic
Acidic
[H+] > [OH-]
[H+] < [OH-]

10. IV. Enzymes
Enzymes are proteins that act as organic biological catalysts by speeding up the rate of chemical reactions (breaking/forming of bonds).
1. They work by lowering the amount of energy needed to start a reaction
(activation energy)
2. They are reusable.

11. B. Substrate: what an enzyme breaks down or puts together.
Ex: Maltase – the enzyme that works with the sugar, maltose
The first part of the enzyme name indicates the substrate
that it works with.
Enzyme names end in -ase
glucose
glucose
Maltose
Maltase
Enzyme-Substrate
Complex

12. Dehydration Synthesis
Substrate
Enzyme
Enzyme-Substrate Complex

13. Hydrolysis
Substrate
Enzyme
Enzyme-Substrate Complex

14. C. Enzyme activity: 1. The Enzyme – Substrate Complex:
a. Lock and Key Model – enzymes work on specific substrates
*Each enzyme (“lock”) has an active site with a specific shape in which the substrate (“key”) fits.

15. b) Induced Fit – the active site closes snugly around the substrate.
*like a hand catching a ball
2. Coenzymes: bind to the active site to help enzymes do their job.
*vitamins are coenzymes

16. D. Factors affecting enzyme activity:
*each enzyme works best in certain conditions.
The concentration of enzymes vs. substrates –
how often they bump into each other.
PICTURE

17. 2. Temperature: as temperature increases, the rate of
reaction increases…..
*but if it gets too hot…
the enzyme denatures
(changes shape) and no longer functions
37°C = Body Temp.
Above 40°C = Denatures

18. 3. pH Level: Enzymes work best within a certain pH range.
*if the pH is too low or too high, the enzyme will denature.