2.2 Flashcards
microbial structure: appendages
What are the three appendages that microbes can have?
- flagella
- pilus
- fimbriae
What are flagella?
An appendage that mores in a propeller fashion that is embedded into the cell membrane and cell wall
- The primary function is locomotion
- can be a sensory organelle
- Run & Tumble: run the initial movement of
flagella moving CCW and tumble to sense the
surroundings; flagella move CW
How are spirochetal endoflagella different from actual flagella?
diderms: flagella in spirochetes are embedded into the cell membrane and peptidoglycan layer but remain in the periplasmic space (does not leave the cell, stays within)
- essentially gram-negative but not LPS/LOS
ex. treponema pallidum & borrelia burgdorferi
What is the type III secretion system?
specialized flagella that secrete virulence factors, found in many gram (-) microbes
- attachment proteins
- toxins
- immune evasion
Needle is already out and ready to puncture host membrane
What are pili?
appendages that emerge from the cell surface
- movement
- secretion
- conjugation
- attachment
What is the type IV pilus?
the primary function of motility
- more rigid, twitching
- exhibits crawling or walking moves
What is the type IV secretion system?
secrete virulence factors, transfer & uptake DNA, potentially “steal” resources from the host
- only extends when it senses host cell
- both gram (-) & (+)
what is the type VI secretion system?
secrete virulence factors into the target cell; similar to bacteriophage
- JUST CALLED AN APPENDAGE
What does the conjugation pilus do?
transfer genetic material from donor to recipient cell
- secretion system 4 mediates this process
- sex pilus or F pilus
- encoded by F factor (fertility factor)
ex. antibiotic resistance plasmid can be transferred, not part of actual DNA
What are Fimbriae?
specialized pili whose main function is adherence and releases vital pathogen virulence facto; colonization factor antigen (CFA)
- grabs ahold of receptors and attach proteins to colonize host cell
- grabs onto multiple microbes to further colonize
What is afimbrial adhesion?
attachment without fimbriae
- adhesions found on cell wall
ex. glycocalyx
Atrichous
no flagella
monotrichous
one flagella
amphitrichous
two flagella, one on both ends
peritrichous
multiple flagella all around
lophotrichous
3 flagella at one end
cephalotrichous
3 flagella at both ends
