This has been the visit to this site since Sept. 19, 1996.

OUTLINE:
THE CELL
CELL SIZE
PROKARYOTIC CELLS

CELL WALL
PLASMA MEMBRANE
CAPSULE
PILI

PLANT vs. ANIMAL CELLS
FUNGAL CELLS
PROTIST CELLS
NUCLEUS CHROMOSOMES
CHROMATIN
NUCLEOLUS

THE CELL IS TO BIOLOGY WHAT THE ATOM IS TO CHEMISTRY.

PROKARYOTIC vs. EUKARYOTIC CELLS

EUKARYOTIC CELLS: eu (G) = true; karyon (G) = kernal

Nucleus bounded by nuclear envelope
Membrane bound organelles
Cells of plants, animals, fungi and protists
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No nuclear envelope
No membrane bound organelles
Cell type of true Bacteria and the Archaebacteria

Mycoplasma 0.1 - 1 micrometers (cause types of pneumonia and urogenital infections)
Bacteria 1.0 - 10 micrometers
Eukaryotic cells 10 - 100 micrometers

In general Eukaryotic cells are much bigger than prokaryotic.
Lower limits on size imposed by requirement to fit everything in the cell,
Upper limit in size determined by surface to volume ratio problem. Exchange surface for gases, nutrients and waste --- molecular diffusion
(Fig. 7.5)

Eukaryotic cells have a lot of internal membrane-bound compartments to compensate for their lower surface to volume ratio.
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Chapter 25 (Pgs. 498-504)= new reading assignment
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Prokaryotes may be unicellular, colonial or show simple multicellular morphologies.
Most bacteria are spherical, rod shaped or spiral shaped.

See fig 7.4 Shows basic structures of a simple bacterium.
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Box PAGE 501 Gram + = Has thick peptidoglycan layer
(29967) Gram - = Has outer membrane
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Capsule = A gelatinous polysaccharide secretion that protects some bacteria
Pili = Surface appendages for adherence or for transfer of DNA
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Bacteria also often have internal membrane systems attached to the plasma membrane.
Esp. true of photosynthetic bacteria (Cyanobacteria) and other autotrophic bacteria.
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Usually use flagella which are semi-rigid and made of a protein call FLAGELLIN
A Flagellum is hooked into a basal body that acts like a rotary motor that causes the bacterium to move through liquid in a cork-screw manner. This is very different than the way Eukaryotic cells move.
(fig. 25.4)
PLAY Video 33891
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Some bacteria are actually spiral shaped and their whole body acts like a cork screw.
Some bacteria can exhibit gliding motility along little slime trails.
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Review the importance of compartmentalization.

PLANT vs. ANIMAL CELLS:

3 things not found in Animal cells:
1) Chloroplasts,
2) Central Vacuole
3) Cell Wall (cellulose)

(Figs. 7.7 and 7.8)

FUNGAL CELLS have CELL WALLS (chitin or cellulose), but no chloroplasts
PROTIST CELLS are like animal cells.
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CHROMOSOMES are made of CHROMATIN (= DNA and Histone proteins) humans have 46 chromosomes in their nuclei.

NUCLEOLUS = Region of the Nucleus where RIBOSOMES are made (up to 10,000 per minute)
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Contains about 1/1000 the amount of DNA as our Nucleus.
Consists of one double stranded circular DNA molecule.
Not found in a nucleus.

Smaller rings of DNA that code for supplemental cellular functions such as resistance to antibiotics or sexual characteristics of bacteria.

back to PROKARYOTIC and EUKARYOTIC CELLS:

CYTOPLASM = Region between the Nucleus and the Cell Membrane (where things like ribosomes are found)
CYTOSOL = Semi-fluid medium found in the cytoplasm.
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They are made of rRNA and proteins. Prokaryotic ribosomes are smaller than eukaryotic.

Ribosomes are either FREE or BOUND to the ENDOMEMBRANE SYSTEM

FREE RIBOSOMES make proteins that function in the cytosol
BOUND RIBOSOMES make proteins that function in membranes or are exported.