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31 Cards in this Set
- Front
- Back
Coccus
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Circular/spherical
Diplo and strepto (1 plane) Tetrad (2 planes) Sarcina (3 planes) Staphylo (>3 planes) |
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Bacillus
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Long, rod-shaped
Only divide in one plane, limited arrangements: Diplo (2 bacilli joined together) Strepto (chain of bacilli) |
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Vibrio
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crescent-shaped
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Spirillum
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spiral
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Spirochaete
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tight spiral
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Glycocalyx
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High molecular weight polysaccharide &/or protein coat surrounding most bacterial species
Secreted; deposited outside cell wall Slime layer (loosely attached/unorganized) or capsule (firmly attached/organized) |
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Functions of glycocalyx capsule
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Can be a virulence factor: prevents cell from being washed away, capsule becomes part of biofilm/protects against chemical/antibiotic entry
Prevent desiccation Source of nutrition Evade immune cells |
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Function of glycocalyx biofilm
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Difficult to remove; common way bacteria grow in nature
Protect cells against physical forces and chemicals Allows for cell-cell communication |
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Flagella
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Long, thin helical filament(s); one end attached to cell, other end free
Base of each filament contains rotary motor Propels bacteria through liquid 4 arrachngements: Monotrichous (one on end) Amphitrichous (one on both ends) Lophotrichous (multiple on one end) Peitrichous (multiple, various locations) |
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Axial filaments (endoflagella)
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Spirochaetes only:
-Borrelia burgdorferi -Treponema pallidum Bundles of flagella anchored at either pole -winds around cell between CM and OM Filament rotates, cell turns in corkscrew manner, cell propelled |
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Fimbrae
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pilin protein
shorter than flagella used for: attachment to surface, twitching motility |
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Sex pili
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pilin protein
longer and fewer in number than fimbrae used for Conjugation |
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Gram positive cell wall
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thick peptidoglycan
teichoic acids Lipoteichoic acids No outer membrane |
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Gram negative cell wall
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Thin peptidoglycan layer
Outer membrane: lipid bilayer, lipopolysaccharide (Lipid A, Core polysaccharide, O side chain), Porins Gram negative cells have a periplasmic space |
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Peptidoglycan structure
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Bacteria only
Function: rigidity Contains sugars and peptides 2 sugars: NAM and NAG Adjacent glycan chains connected by peptide cross link |
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Peptide cross link
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Short peptides connecting NAMs in adjacent glycan chains
Consist of D and L amino acids Differ between gram pos and gram neg G neg: diaminopimelic acid (DAP), tetrapeptides linked by SINGLE peptide bond G pos: no DAP, tetrapeptides linked by glycine interbridge |
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The cell wall of a gram negative bacterium consists of a thin layer of peptidoglycan and an outer membrane. The outer membrane consists of:
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a lipid bilayer and porins.
The lipid bilayer consists of one layer of phospholipids and one layer of lipopolysaccharide (LPS): lipid A, core polysaccharide, and O side chain |
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Teichoic acids
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Gram positive cell wall
phosphorylated alcohols (-) unknown function, might facilitate transport of (+) charged substances into cell |
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Lipoteichoic acids
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gram positive cell wall
teichoic acids with lipids bound to them Function: anchor peptidoglycan to cell membrane |
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Lipid bilayer
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Gram negative cell wall
two layers of lipids Amphipathic (one hydrophilic end, one hydrophobic end) molecules build lipid bilayers |
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O side chain
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gram negative cell wall
Contains sugars, varies among bacteria Sugars have (-) charge, responsible for g(-) cells being neg charged Function: attachment to surfaces |
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Mycoplasma
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Atypical
Smallest independently producing bacteria No CW CM has sterols (strengthens/prevents osmotic lysis) |
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Archaea
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Atypical
Often CW but NO peptidoglycan no cell wall, thermoplasma If cell wall, diverse gypes (ex: pseudopeptidoglycan) |
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beta(1,4) bond
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bonds glycan chain, G-M bond
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mycobacterium
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atypical
cell wall = 60% mycolic acid (acid fast +) Increased resistance to antibiotics and cell wall degrading components of the immune system |
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Cytoplasmic membrane in bacteria
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Phospholipid bilayer (glycerol)
Proteins (phosphate group -> negative charge) Hopanoids (sometimes--long chains of H-C, Hydrophobic) |
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Peripheral proteins
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not embedded
attaches to CM via lipoprotein Surface Easily removed chemically w/o disrupting membrane |
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integral proteins
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embedded in CM to some extent
must destroy membrane to remove |
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Prokaryotic vs. Eukaryotic membranes
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usually no sterols in prokaryotic membranes
Many bacteria hopanoids instead (similar to sterols, embedded in CM, increase CM strength/rigidity) |
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Archaea vs. Bacteria membranes
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Arachae:
ether-linked lipids (vs. ester-linked lipids in bacteria) Isoprene units (vs. fatty acids in bacteria) Some have lipid monolayers (vs. no monolayers in bacteria) |
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Functions of cytoplasmic membrane
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selectively permeable
Anchors proteins Generation of electrical gradient (i.e. proton motive force) |