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42 Cards in this Set

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  • Back
difference between prokaryotes and eukaryotes
prokaryotes lack membrane-bound organelles
2 major disease-causing groups of unicellular eukaryotes
fungi
protozoans
4 structures common to all bacteria
murein (peptidoglycan) cell wall
exoproteins
cytoplasmic membrane
ribosomes, both free and attached to surface of cytoplasmic memrane
characteristics of bacterial endoskeleton
found in rod-shaped bacteria
homologous to actin cytoskeleton of eukaryotic cells
why do bacteria need a murein cell wall?
to prevent cell lysis:
solute conc in bacterial cytoplasm is much higher than solute conc in bld/ECF of host cell
structure of murein cell wall
1 molecule of murein surrounds the entire cell
peptide component and glycan component: peptidoglycan
glycans = polysaccharides
individual glycans cross-linked by peptides 4-5 a.a.s long
cross-linking
individual glycans (polysaccharides) of the murein cell wall are cross-linked by peptides 4-5 a.a.s long
Why are Mycoplasma different from all other bacteria?
crippled: no murein cell wall
therefore, don't survive in environments without high solute concentrations
need to be cultured with osmotic stabilizers, e.g. sucrose
significance of exoproteins
virulence factors
can be secreted from bacterium or remain adhered to the bacterial cell
interact with and damage host cell
distinguish gram negatives from gram positives
gram negatives: outer membrane with LPS
gram negatives: no outer membrane; THICK murein wall with teichoic acid
teichoic acid
polysaccharide chains
located in murein cell wall of gram positives
diagnostic b/c highly antigenic
diagnostic b/c differ from species to species
group-specific antigen vs. type-specific antigen
both are virulence factors in gram positives
group-specific antigen identifies 1 grp of Streptococcus from another (e.g. C polysaccharide of Streptococci)
type-specific antigen identifies 1 type of virulence from another (e.g. M protein of group A Strep)
name the 6 gram positive organisms
(all the rest are gram negative)
Streptococcus
Staphylococcus
Bacillus
Clostridium
Corynebacterium
Listeria
C polysaccharide of Streptococci
example of group-specific antigen
M protein
example of type-specific antigen; major virulence factor of Streptococci
allows subtyping of beta-hemolytic Streptococci
characteristics of gram positives
thick murein cell wall; no outer membrane
teichoic acid polysaccharide chains
group-specific antigens, e.g. C polysaccharide of Streptococci
type-specific antigens, e.g. M protein of Streptococci
characteristics of gram negatives
bilayer outer membrane with LPS and OM proteins
periplasmic space with periplasmic proteins
2 roles of outer membrane proteins
virulence factors / adhesion to host cell
porins (aqueous channels)
periplasmic proteins
in periplasmic space of gram negatives
enzymes, e.g. beta-lactamases
LPS
lipopolysaccharide in outer membrane of gram negatives
composed of:
lipid A endotoxin
core polysaccharide
O-antigen (=polysaccharide)
lipid A
endotoxin
highly toxic component of LPS in the outer membrane of gram negatives
conserved among gram negatives
core polysaccharide
1 component of LPS in outer membrane of gram negatives
common to all gram negatives
no known role in pathogenicity
O-antigen
1 component of LPS in outer membrane of gram negatives (=polysaccharide)
variable among gram negatives and therefore diagnostic
virulence factor: inhibits phagocytosis
name 3 optional structures of bacteria
pilus
flagellum
capsule
flagellum
motility - propeller
not a clear virulence factor
H antigen can be used for typing
H antigen
antigenic determinant that makes up subunits of flagella
can be used in typing
pilus
rod-like protein structure
virulence factor: tip of structure is specific for binding and adherence to host
found in cytoplasmic membrane (g+) or outer membrane (g-)
capsule
virulence factor: inhibits phagocytosis
large mucoid structure (no organelles) that surrounds cell
amost always made of polysaccharide chains
mutation causes loss of capsule causes loss of virulence
bacterial spores
metabolically inactive form of bacteria
spore coat prevents toxic elements from entering cell
sporulation triggered by environmental cues
cytoplasmic changes in sporulation
water loss
altered composition of DNA and proteins
lipid A
endotoxin
highly toxic component of LPS in the outer membrane of gram negatives
conserved among gram negatives
core polysaccharide
1 component of LPS in outer membrane of gram negatives
common to all gram negatives
no known role in pathogenicity
O-antigen
1 component of LPS in outer membrane of gram negatives (=polysaccharide)
variable among gram negatives and therefore diagnostic
virulence factor: inhibits phagocytosis
name 3 optional structures of bacteria
pilus
flagellum
capsule
flagellum
motility - propeller
not a clear virulence factor
H antigen can be used for typing
H antigen
antigenic determinant that makes up subunits of flagella
can be used in typing
pilus
rod-like protein structure
virulence factor: tip of structure is specific for binding and adherence to host
found in cytoplasmic membrane (g+) or outer membrane (g-)
capsule
virulence factor: inhibits phagocytosis
large mucoid structure (no organelles) that surrounds cell
amost always made of polysaccharide chains
mutation causes loss of capsule causes loss of virulence
bacterial spores
metabolically inactive form of bacteria
spore coat prevents toxic elements from entering cell
sporulation triggered by environmental cues (nutrient deprivation)
cytoplasmic changes in sporulation
water loss
altered composition of DNA and proteins
vegetative cell can undergo either _____ or _____
sporulation (nutrient deprivation) or
germination (nl envt)
how do you induce germination of a sporulating cell back to a normal vegetative cell?
feed the organism