Bacterial Cell Flashcards
What are the main functions of the capsule?
Layer that functions in adherence and immune evasion
What are strong antigens on bacteria?
Flagella
What is the cell wall like for Gram +?
It is a thick peptidoglycan wall
What is the cell wall like for Gram -?
It is a thin peptidoglycan wall
What is the function of pili in virulence?
Pili confer virulence by promoting attachment to the host.
What is the function of flagella in virulence?
Motility
What does the envelope consist of?
The envelope consists of an inner membrane, a cell wall (the peptidoglycan) and, in the case of Gram - envelopes, an outer membrane.
Inner Membrane
The inner membrane is common to both Gram - and Gram + envelopes. It consists of a lipid bilayer comprising phospholipids and proteins.
Outer Membrane
The outer membrane is unique to the Gram - envelope. Like the inner membrane, it is a bilipid layer, but the outer leaflet has lipopolysaccharide (LPS) molecules instead of phospholipids.
Porins
Porins are structures unique to the outer membrane that allow passive entry and exit of small molecules.
What makes LPS toxic?
Lipid A
How do Clostridium perfringens spores cause disease?
The production of a spore by a stressed cell will directly result in disease as in food contamination
How do Bacillus anthracis spores cause disease?
Spores must convert back to a normal growing cell (germination) before they cause disease symptoms
Mycoplasma
A very simple cell type that has only an inner membrane, of special composition. Because it lacks the peptidoglycan, it can have a variety of shapes.
Biofilms
Biofilms are organized multicellular bacterial
communities that coordinate via pheromones and are difficult to deal with as they are protected from antibiotics
How do the biofilms change in the GI tract and why?
In human, biofilms are most prominent in the proximal colon and appendix. Biofilm levels decline toward the distal colon.
Possibly, the interactions between biofilms and IgA differ between the proximal and distal colon. If some feature of IgA allows it to better bind bacteria in the distal colon, this could inhibit bacterial deposition at that site.
What is the difference in the flagella of ETEC bacteria?
ETEC flagella replace the cap with an adhesin.
What is a therapeutic strategy to defeat biofilms?
Apply a drug that blocks pheromone communication among bacteria in the biofilm.
