intro- bailey Flashcards
what type of bacteria can grow in both aerobic and anaerobic environments?
Facultative anaerobes
which class of aerobes are most important to medicine?
facultative anaerobes
under what conditions to Oligotrophs grow? Microaerophiles? Mesophiles?
Oligotrophs- can grow with limited nutrients
Microaerophiles- requires low oxygen levels
Mesophiles- grow well in mild temperatures
what type of bacteria have a thick layer of peptidoglycan?
gram-positive
what is the general structure of Murein?
long strands of N-acetylmuramic acid and N-acetylglucosamine
-all cross-linked with peptides
what is NAM? where is it found?
1) N-acetly muramic acid
2) found on gram-positive bacteria
where are NAG and NAM produced? where does elongation occur?
1) in the bacterial cytoplasm
2) elongation occurs in the periplasmic space
what 2 acids are found on the outer surface of gram+ bacteria? (outer layer of the cell wall)
Teichoic acid and lipoteichoic acid
what is the outer layer of gram negative bacteria?
LPS- lipopolysaccharide
where do teichoic acids attach on the cell wall? lipoteichoic acids?
teichoic acids- attach to NAG and NAM
lipoteichoic acids- extend into lipid membrane
what are the 3 regions of a LPS molecule?
from internal to external:
1) Lipid A
2) Polysaccharide core
3) O-antigen
which subunit on LPS shows the most variability?
the O-antigen
what substance is produced in response to LPS? (hint: causes toxic shock syndrome)
TNF-alpha
what receptor recognizes LPS?
Toll-like receptor 4 (TLR4)
what receptor recognizes peptidoglycan?
Toll-like receptor 2 (TLR2)
which receptor recognizes teichoic acids?
toll-like receptor 2
name the other 3 extracellular structures
1) flagella
2) Pili (fimbriae)
3) glycocalyx
what structure involved in the attachment of bacteria to other surfaces?
Pili (fimbriae)
what are Adhesins?
specilized proteins on the tips of fimbriae. Made specifically for adhesion to other surfaces/cells
what are the 3 classes of flagella?
1) monotrichous
2) Lophotrichous
3) Peritrichous
name the 4 basic structures of a flagella/fimbriae
Filament, Hook, rod, movement proteins
what is taxis?
directed movement toward/away from a stimulus
name the 4 types of taxis
1) chemotaxis
2) Aerotaxis
3) Osmotaxis
4) Thermotaxis
what is a capsule
a well-organized, firmly attached Glycocalyx
what is a slime layer?
a glycocalyx that is not firmly attached or well-organized
how can a capsule act as a virulence factor for bacteria?
They can hide the cell from our bodies immune system, or create a large/bulky covering that makes it difficult for microphages to ingulf them
which cytokines are released when a bacteria is recognized?
IL-1, IL-12, TNF-alpha
name the 2 classes of bacterial pathogens
Opportunistic and Primary
name the 2 types of non-specific adherence
Reversible and Docking
give examples of docking adherence
1) Browning’s movements (random interactions)
2) electrostatic attractions
3) interaction with glycocalyx
what does specific adherence require?
adhesins
what do the adhesins of streptococcus mutans bind to?
the pellicle of teeth
what adhesin is not found on fimbrae?
Fibronectin- found in plasma
how do bacteria “take up” nutrients?
- Carrier-mediated diffusion (facilitated)
- Phosphorylation-linked transport (group translocation)
- Active transport (energy dependent)
what is Enteropathogenic E. coli (EPEC) a prime example of?
colonization inducing tissue pathology- leads to actin polymerization
what are the 2 main mechanisms for bacterial colonization/invasion?
secretion of hyaluronidase and collagenase.
Endotoxins:
Not secreted. They are on the surface of the bacterium.
Lipopolysaccharide is the most common (that’s why people call it endotoxin).
Exotoxins
Exotoxins are diffusible proteins that are secreted. 3 main types (type 1, 2, 3)
what makes a microbe a pathogen?
Ability to adhere to host. Ability to colonize the host. Ability to replicate within given niche. Ability to cause damage. Invasion Production of toxin Activation of the immune system
