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Flagella and pili are what?
External structures extending from the cell membrane through the cell wall and beyond it.
Flagella (pl), Flagellum (sin)
- External structure as way of movement w/speed and apparent purpose.
- Long, thin, helical appendages.
- Composed of flagellin - Protein subunits.
- Basal region.
- Bacteria w/ a single flagellum located at one end /pole.
- Bacteria w/ 2 flagella, one at ea. end/pole.
Bacteria w/ 2 or more flagella at one or both ends.
Bacteria w/ flagella all over the surface.
- Bacteria w/o flagella.
- Cocci rarely have flagella.
Flagella: Gm (+)
- 2 rings =
- 1 outer protein ring to cell wall/thick peptidoglycan.
- 1 inner protein ring to cell membrane.
- Attachement site for flagellum.
- Consists of protein other than flagellin.
- Contains hooklike structure and basal body.
- Basal Body - central rod/shaft surrounded by a set of rings.
Flagella: Gm (-)
- 3 main parts = filament, hook, basal body.
- Basal body: 2 outer rings + rod + 2 inner rings
- 4 rings =
- 2 Outer rings: Cell wall = outer membrane + peptidoglycan
- 2 Inner rings: Cell membrane; lipopolysaccharide
Bacteria move toward or away from substances in their environment by a nonrandom process.
- Moving --> attractant - lengthen runs, reduces freq of tumbles.
- Moving <-- attractant - shortens run, inc freq of tumbles.
- lower [harmful subs] <-- repellant - longer runs, few tumbles
- higher [harmful subs] <--repellant - short urns, many tumbles
- External motility structure composed of axial filaments; lie between outer sheath and cell wall; anchored at one end of a cell.
- Spirochete - corkscrew rotation movement
Pili (pl) , Pilus (sin)
- Tiny hollow projection that allow attachements to surfaces. Not involved in movement.
- 2 kinds...
- AKA - F pili / sex pili.
- Donor cell forms hollow bridge between similar bacterial cells for DNA transfer.
- One of the sources of antibiotic-resistant baceria.
- AKA - Attachment pili
- Contribute to the pathogenicity (ability to produce disease) by enhancing colonization.
- N. gonorrhoeae - attaches to epithelial cells of urogenital system.
- Pellicle - Aerobic bacteria forming a shiny/fuzzy thin layer at the air-water interface of a broth culture.
- All polysaccharide containing substances found external to pro. cell wall. Usually sticky.
- Capsules - most organized and thickest, prevents phagocytosis, increases pathenogenicity.
- Slime Layer - unorganized, thin, loose. All bacteria have at least a thin slime layer.
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