I. Cell theory

II. Eukaryotic vs. prokaryotic cells

III. Cell structure

IV. Cell-cell communication

V. Plant vs. animal cells

Cells: structure and function

I. Cell theory

All living things are composed of cells and cells form a unifying structural basis of organization (1838).

-- Structure and function (1900s)

-- All cells come from preexisting cells (1862)

-- no nucleus -- have a nucleus

-- have membrane bound organelles

-- no membrane bound organelles

-- plant and animal cells -- bacterial cells

II. Eukaryotic vs. prokaryotic cells

Eukaryotes Prokaryotes

Fig. 3.4, p. 33

Remaining organelles

Cytoplasm =

Protoplasm =

Cell =

III. Cell Structure:

Subunits of the cell

Cell wall

Cytosol = fluid of the cell

Vacuole

Nucleus

A. Cell wall

-- defines the shape of the cell

Secondary cell wall

Primary cell wall

Middle lamella

Intercellular space

A. Cell wall

Rigidity = strength, support, and protection

“cellulose fibrils”

2. Primary cell wall: network of cellulose, hemicellulose,

pectin, glycoproteins3. Secondary cell wall: derived

from primary wall, include lignin

1. Middle lamella: layer of pectin

B. Plasma membrane:

-- selectively permeable: regulates the movement of substances into and out of the cell

-- Composed of lipids, protein and carbohydrates

Fig. 3.7, p. 37

carbohydrates

lipidsproteins

C. Organelles

1. Nucleus (pl. nuclei)

-- Stores hereditary material (DNA)

-- “Control center” of the cell

2. Vacuole

-- Stores water, nutrient reserves, excess minerals, and toxic waste

-- Recycles cellular materials

-- Maintains pressure

3. Mitochondria (sing.: mitochondrion)

-- “Powerhouses” of the cell; site of cellular respiration

Fig. 3.13, p. 42

4. Endoplasmic reticulum (ER):

-- Network of membrane channels; carry material around the cell

ribosomes

-- Rough ER: protein synthesis

-- Smooth ER: lipid secretion, membrane assembly

5. Ribosomes

-- responsible for protein synthesis

6. Plastids

a. Chloroplast: “green”

-- Photosynthesis

-- Chlorophyll pigment

b. Chromoplast: “color”

-- Carotenoid pigment (yellow, orange, red)

c. Leucoplast: “colorless”

-- Store starch and oils

7. Dictyosomes (Golgi bodies)

-- Flattened membrane sacs

-- Process products of the ER

-- “post offices” of the cell

vesicles

-- through secretion of specific compounds

IV. Cell-cell communication

-- through plasmodesmata (sing.: plasmodesma):

cytoplasmic channels between adjacent cells

Fig. 3.20, p. 50

V. Plant vs. animal cells

Plasma membrane = Cell membrane

Nucleus Nucleus

ER ER

Ribosomes Ribosomes

Mitochondria Mitochondria

Dictysomes = Golgi

Cell wall

Large central vacuole

Plastids (ex. chloroplast)

Plasmodesmata

Plant cells Animal cells