Transcript Prokaryotic Anatomy I: Capsule, Flagella, Fimbriae, and Fili

Prokaryotic Anatomy I:
Capsule, Flagella, Fimbriae, and Fili
Nestor T. Hilvano, M.D., M.P.H.
Learning Objectives
You should be able to:
1. Describe the four major processes of living cells.
2. Classify prokaryotes as to shape and arrangement.
3. Compare and contrast prokaryotic and eukaryotic
cells.
4. Describe the composition, function, and relevance to
human health of glycocalyces.
5. Distinguish between capsules and slime layers.
6. Discuss the structure and function of prokaryotic
flagella.
7. List and describe four prokaryotic flagellar
arrangements.
8. Compare and contrast the structures and functions of
fimbriae and pili.
Prokaryotes
• 3 basic bacterial morphology:
a.) cocci, b.) bacilli, and c.) spirals
• Spirals can be stiff (spirillum) or flexible (spirochetes)
• Exercises:
Give the shape/morphology of organisms:
__ helical;
__rod-like;
__oval or round
a. bacillus
b. coccus
c. spiral
• Archaea = similar to bacteria, except it lack
peptidogylcan cell walls and survive in extreme
environment; no known disease in human; importance in
industrial application ( thermophiles and their enzymes
are used as additives in laundry detergents), and
methanogens (methane traps heat, can lead to global
warming; useful in sewage treatment)
Major Processes of Living Cells
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Growth Reproduction Responsiveness Metabolism -
* Viruses –inert agent; have no cellular
structure (nonliving protein, nucleic acid)
Compare Eukaryotes & Prokaryotes
• ___ What cells lack nucleus and membrane –
bound organelles, and are small (1 um or less in
diameter)
External Structures: Glycocalyces
• Gelatinous, sticky substance
• Importance= ability to survive/protection and to
cause disease
• Types of glycocalyx:
a. Capsule- thick, firmly attached to cell surface for protection;
ex: streptococcus pneumoniae
b. slime layer- thin (loose), water
soluble for protection from drying;
ex: oral bacteria/biofilm cause
tooth decay
External Structures: Flagella
• Long, whiplike structure protruding from a cell
• Cell’s motility
• Parts:
- Filament, Hook, and Basal Body(rod and protein rings)
• Rotate 360°
• Serovars- species strains
* Gram + =single pair of rings
* Gram - = 2 pairs of rings
Flagellar Arrangement
Exercises:
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___ - no fagella
___ - Flagella all over
___ - 2 flagella one each end
___ - Tuft of polar flagella
___ - Single polar flagellum
a. Monotrichous
c. Amphitrichous
e. Atrichous
b. lophotrichous
d. peritrichous
* Endoflagella form axial filaments, corkscrew thru it’s medium
(ex: spirochetes agent of syphilis)
Flagellar Function
• Rotate either clockwise or counterclockwise
- Runs (straight; counterclockwise rotation)
- Tumbles (random change in direction;
clockwise rotation)
• Taxis – movement towards a stimulus
(phototaxis or chemotaxis)
• Increase runs closer to concentration;
increase tumbles farther away from
concentration
External Structures: Fimbriae
• Short, sticky, proteinaceous, non-motile
extensions
• To adhere to one another, host, environment
(Neisseria gonorrhoeae attached to mucous membrane of
reproductive by fimbriae)
• Important function in biofilms
External Structures: Pili
• For attachment; longer than fimbriae, shorter than
flagella
• Hollow, non-motile tubules of protein
• Conjugation pili (F pili or sex pili) – mediate transfer of
DNA/other substrate
• Attachment pili (adheres to surfaces)- join bacterial cells
Homework
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Definition of terms: spirillus, spirochetes, taxis,
capsule, flagellum, prokaryote, fimbriae, slime layer,
glycocalyx, pili, and biofilms.
Differentiate prokaryotic from eukaryotic cells as to
relative size, nucleus, and membranous organelles.
Classify the shape of microbes: a) helical; b) rod-like;
c) oval
Give the importance of archaea.
How do flagella of gram negative bacteria differ from
gram positive bacteria?
Describe flagellar arrangement.