Chapter 3: Cellular Form and Function

Section 3.1

Cytology:

2 Classes of Cells

1) Sex Cells

2) Somatic Cells

Basic Components of a Cell

1) Plasma Membrane

2) Cytoplasm

a. Cytosol (Intracellular Fluid)

i. 55% cell volume

ii. Components: 75-90% water with dissolved and suspended components

iii. Differences from ECF

1. Higher K+, lower Na+

2. Higher protein concentration

3. Stores organic molecule reserves

b. Organelles (See posted summary table for need to know information. The functions for

the “need to know for lecture exam 1” organelles matches what you already need to

know about them for lab.)

3) Nucleus

Section 3.2

Plasma Membrane

1) Basic Functions

a. Physical isolation

b. Regulation of exchange with the environment

c. Sensitivity to the environment

d. Structural support

e. Forms organelles

f. Cell communication

2) Membrane lipids (form 98% of membrane molecules)

a. ~ 75% Phospholipid bilayer

i. Polar molecules and ions cannot cross lipid portion of membrane

b. ~ 20% Cholesterol

c. ~5% Glycolipids

3) Membrane is neither rigid or uniform

a. Consistency of olive oil

i. Why important?

ii. Control of fluidity

1. Double bonds in fatty acids

2. Cholesterol

4) Membrane Proteins (55% of membrane weight)

a. Specialized functions

i. Cell-adhesion molecules