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What are the 3 main shapes of bacterial cells?
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Coccus - round
bacillus - rod shaped spiral - curved |
Arrangement: diplo-
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Pairs
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Arrangement: strepto-
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Chains
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Staphyl-
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Clusters
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Positions within cell
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Central
terminal subterminal (near end) |
Sticky sugar substance; sometimes protein
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Capsule
-present or absent |
Cell surface includes:
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Cell wall (LPS)
flagella fimbriae pili capsules |
-adherence to host tissues
-resist phagocytosis -immune response -induce inflammation -resistant to drugs |
Important in pathogenesis
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Extracellular gelatinous substance (viscous polymer)
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Glycolalyx
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-surrounds cells
-most are polysaccharides (sugars), some are polypeptides (proteins) in loose gel -in both G+ and G- bacteria |
Glycolalyx
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-adhesion/attachment- to other cells (bac + host) as well as biofilm
-reserve of nutrients or protection against dessication -virulence factor |
Virulence factor
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-intensity of disease produced by pathogen capsule prevents phagocytosis by immune system, also important for adherence to host tissues
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Virulence factor
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-functional consortium of bacteria organized within an extensive exopolymer matrix
-extremely resistant to clearance by human immune system and antibiotics -many human disease associated with these (up to 65%) |
Biofilms
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3 types of appendages:
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Flagella
fimbriae pili |
Flagella
fimbriae pili |
Motility
adhesion (sometimes aka common pili) (sex pili) |