Endospores

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Endospores
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Cytoskeleton Within the last five years it has
become clear that bacteria do have a true
cytoskeleton including actin-like (MreB) and
tubulin-like proteins. Most bacteria actually get
their cell shape from the cytoskeleton, NOT from
the peptidogylcan layer as previously
thought. Necessary for Cell division DNA
segregation Cell Shape So . . . Is MreB an
ancestral form of actin or is it a case of
co-evolution?
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Gas vesicles Surrounded by protein sheath that
excludes water used for buoyancy
Storage particles (Store
nutrients and essential elements) Glycogen/
Starch Poly-b-hydroxybutryic acid (PHB)
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Cell Layers Cytoplasmic Membrane Water and
ion impermeable Fluid Mosaic
Model temperature sterols bacterial
vs. archaeal membranes
Isoprenoid Based Ether linked
Phospholipid Based Ester linked
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Using Centrifugal Force to Separate Cell
Structures
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Cell Wall (Peptidogylcan) A polymer of
acetylated sugar chains X-linked (held together)
by short chains of amino acids Antibiotic
target Was originally though to give the cell
shape Probably serves as a protection against
osmotic shock Varies dramatically in thickness
and rigidity between different groups of
bacteria (basis for Gram stain)
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Differences in Cell Layers Between Gram Positive
and Gram Negative Bacteria
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Bacterial Stains Positive Stain Color the cell
without affecting background, relatively
difficult to do with simple chemical stains can
be done with antibodies or other
molecule specific intreractions Negative
Stain Background is stained, leaving cell
appearing as a bright cavity in a darker
background. Sometimes used in light microscopy,
common in TEM Differential Stain a stain that
allows one to differentiate between bacteria
with different cell structures
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Gram Stain