1. Functional Anatomy of Prokaryotic and Eukaryotic Cells
Chapter 4
Functional Anatomy of
Prokaryotic and Eukaryotic
Cells

2. Definition of “prokaryotic”
Refers to organisms, typically 1-celled, having cells which:
lack a nucleus
lack membrane-bound organelles
contain 1 chromosome
may contain extra-chromomal DNA (plasmids)
contain 70S ribosomes
contain peptidoglycan cell walls

3. Prokaryotic vs. Eukaryotic cells

5. Bacterial cell size, shapes and arrangements
2.0 – 10.0 uM in length
Eukaryotic cells ~10x larger
3 common morphologies
bacillus = rod-shaped
coccus = spherical shaped
spirillum = spiral shaped
Many arrangements
diplo-
strepto-
Staphylo-
***spirochetes**

6. Bacterial morphologies
Morphology can be used as an initial identifier
However, shape can change in some bacteria depending on environs
“pleomorphic” cells

7. Bacterial ultrastructure

8. 1) Cell wall structure
Alternating NAM & NAG amine sugars produce layers of block units
NAM = n-acetylmuramic acid
NAG = n-acetylglucosamine
Layers connected by tetrapeptide chains linked to NAM’s
Penta-glycine interbridges connect tetrapeptides in Gram + cells (sensitive to penicillin)
Direct peptide bonds connect tetrapeptides in Gram – cells (not sensitive to penicillin)
Make up peptidoglycan

9. Alternating NAM-NAG with tetrapeptide connections

10. Gram positive cell wall structure
Ok, not too bad – now for something completely different – Gram negative cell walls!    

11. Gram negative cell wall structure
Gram neg. cell walls are composed of peptidoglycan AND an outer membrane; it is multi-layered!!

12. Gram negative LPS* *Lipopolysaccharide contains 3 parts:
Antigen O – can change shape in dif’t environs
Core polysaccharide – contains neg. charge
Lipid A – also called ‘endotoxin A’; released upon cell death and can have toxic affect on nearby cell membranes

13. Gram pos. vs Gram neg cell walls
Two part structure
Thin peptidoglycan (10-20 nm)
Outer membrane
Outer membrane contains LPS
LPS imparts a negative charge
Thick peptidoglycan
20-80 nm thick
Retains CV-I complex of Gram stain
Teichoic acid anchors cell wall to cell membrane and imparts a negative charge
Glycerol-P polymer

14. The Gram stain

15. 2) Bacterial flagella Composed of: 1) basal body, 2) filament, 3) hook
Basal body connects to cell wall and to cell membrane
Uses ATP to spin

16. Arrangements of flagella

17. Bacteria are hampered to some extent by flagellar rotation