Principles of Biology - Biology 101
Fall Quarter
Lake Tahoe Community College
Instructor: Sue Kloss
_______________________________________________________________________________________________
Chapter 3: Water
_______________________________________________________________________________________________
Water: the molecule that supports all of life
I.
Polarity of water
A. Oxygen’s electronegativity
B. water molecule shape
II.
Emergent properties of water
A. Cohesion
1. H bonds
2. bonds break and reform
3. cohesion
4. adhesion
6. surface tension
B. Moderation of temperature
1. Heat and temperature
a. heat vs temperature
2. Specific heat
a. calorie
b. water’s specific heat
3. Evaporative cooling
a. evaporation or vaporization
b. water has a high heat of vaporization
c. evaporation cools
C. Becomes more dense, then less dense as it gets colder
1. At temps above 4 C
2. as temp falls to 0C ice is less dense than water
3. if ice didn’t float
4. floating ice insulates
D. Solvent
1. solutions
a. solvent
b. solute
c. aqueous solution
d. hydration shell
f. non polar molecules and water
g. the solvents of life
2. hydrophyllic and hydrophobic substances
a. hydrophyllic
b. hydrophobic
3. Solute concentration in Aqueous Solutions
a. molecular mass
b. mole = 6.02 x 1023 and there are 6.02 x 1023 daltons in a gram
c. molecular mass of sucrose is 342
d. molarity
III. Dissociation of water molecules - pH
A. dissociation
1. a H+ ion actually transfers, leaving behind OH- ion (Hydroxide). The other water molecule
becomes a hydronium ion (H3O+)
2. this is reversible, and at equilibrium, pure water only has 1 dissociated molecule/every 554
3. H and OH ions are very reactive
4. acids and bases
5. pH scale
B. Effects of pH change
1. acids and bases
a. acid
b. base
c. some acids are weak, some are strong
C. pH scale
1. In any solution, the product of the H+ and OH− concentrations is constant at 10 −14.
a. Brackets ([H+] and [OH−]) indicate the molar concentration of the enclosed substance.
b. [H+] [OH−] =
c. In a neutral solution, [H+] =
and [OH−] =
d. Adding acid to a solution shifts the balance between H+ and OH− toward H+ and
leads to a decline in OH−.
e. If [H+] = 10−5 M, then [OH−] =
f. Hydroxide concentrations decline because some of the additional acid combines with
hydroxide to form water.
g. Adding a base increases OH− concentration and lowers H+ concentration.
h. H+ and OH− concentrations are typically expressed via the pH scale.
2. The pH scale uses logarithms. Remember that a log is the exponent in a base 10 system.
So the pH scale units differ by an order of magnitude
a. in aqueous solutions at 25C, the product of H+ and OH- is constant at 10-14
1. written as [H+] [OH-] = 10-14 (brackets indicate molar concentration)
b. In a neutral solution, [H+] = 10−7 M, and the pH = 7.
c. You can calculate H+ and OH- concentrations from
d. Acidic solutions have pH values
, and basic solutions have pH values
e. Most biological fluids have pH values in the range of
f. Each pH unit represents a
difference in H+ and OH− concentrations.
g. To maintain cellular pH values at a constant level, biological fluids have buffers
3. Buffers
a. important human blood buffer
Lesson objectives Ch. 3
1. With the use of a diagram or diagrams, explain why water molecules are polar and capable of hydrogen bonding with 4
neighboring water molecules
2. List and briefly describe four characteristics of water that are emergent properties resulting from hydrogen bonding.
3. Define cohesion and adhesion. Explain how water’s cohesion and adhesion contribute to the movement of water from the
roots to the leaves of a tree.
4. Distinguish between heat and temperature, using examples to clarify your definitions.
5. Explain the following observations by referring to the properties of water:
 Coastal areas have milder climates than adjacent inland areas.
 Ocean temperatures fluctuate much less than air temperatures on land.
 Insects like water striders can walk on the surface of a pond without breaking the surface.
 If you slightly overfill a water glass, the water will form a convex surface above the top of the glass.
 If you place a paper towel so that it touches spilled water, the towel will draw in the water.
 Ice floats on water.
 Humans sweat and dogs pant to cool themselves on hot days.
6. Distinguish among a solute, a solvent, and a solution.
7. Distinguish between hydrophobic and hydrophilic substances.
8. Name the products of the dissociation of water and give their concentration in pure water.
9. Define acid, base, and pH.
10. Explain how acids and bases may directly or indirectly alter the hydrogen ion concentration of a solution.
11. Using the bicarbonate buffer system as an example, explain how buffers work.
___________________________________________________________________________________
Chapter 4: Carbon and Molecular Diversity
_______________________________________________________________________________________________
Carbon: the backbone of biological molecules
I. Organic chemistry
A. Living things synthesize organic molecule
II. molecular diversity
A. Formation of bonds with Carbon
1. 6 electrons
2. C usually shares its electrons with other atoms
3. tetravalence
4. molecules are 3D
5. C’s most common bonding partners
a. CO2 may use 2 double bonds
B. Molecular diversity from C skeleton variation
1. C skeletons vary
2. Hydrocarbons
a. organic molecules that have only C and H
b. fossil fuels
c. fats
d. fats and oils are both hydrophobic
3. Isomers
a. structural isomers
b. geometric isomers
c. enantiomers
1. cells can distinguish between these
2. L dopa is effective vs. Parkinsons, while its enantiomer, D dopa, is not
III. Functional groups
The molecular components attached to the C skeleton are important
A. Importance of functional groups
1. functional groups – components of organic molecules most commonly involved in chem. Reactions
a. each functional group behaves consistently from one molecule to the next
b. testosterone and estradiol
2. Important functional groups
a. Hydroxyl
b. Carbonyl
c. Carboxyl
d. Amino
e. Sulfhydryl
f. Phosphate
B. Importance of ATP
1. ATP is the primary energy-transferring molecule in the cell
a. structure
b. if a phosphate ion splits off the molecule
Ch. 4 Lesson Objectives
1. Explain how carbon’s electron configuration accounts for its ability to form large, complex, and diverse organic
molecules.
2. Describe how carbon skeletons may vary, and explain how this variation contributes to the diversity and
complexity of organic molecules.
3. Describe the basic structure of a hydrocarbon and explain why these molecules are hydrophobic.
4. Distinguish among the three types of isomers: structural, geometric, and enantiomer.
Draw a table and include the major functional groups found in organic molecules. Draw the basic structure of
each functional group and outline the chemical properties of the organic molecules in which they occur.
6. Describe how the structure of ATP provides for its function as the molecule providing energy for most
metabolic reactions.
5.