Glossary of bacterial anatomy and physiology
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- 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 (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