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Prokaryotic and Eukaryotic Cells, BACTERIAL MORPHOLOGY, BACTERIAL GROWTH…
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BACTERIAL MORPHOLOGY
ENVELOPE STRUCTURE
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GLYCOLAX
-also called capsule (protects it from dehydration)
- located external of cell wall
- composition: polysaccharides or polypeptide
- slime layer
-indicative of virulence
-aids in evasion of phagocytosis
-can stimulate antibody response
CELL WALL
-Murein sacculus
- Principal component: peptidoglycan ( murein or mucopeptide)
- multilayered in: gram-positive bacteria
-Single layered in: gram-negative bacteria
-provides rigid support and gives shape
-protects: from osmotic damage and plays a role in cell division
Special components of gram-positive cell walls
- Teichoic acids - can elicit antibody response, provides tensile strength
- Polysaccharides - mannose, arabinose, rhamnose and gulcosamine. glucoronic acid and mannuronic acid ( Acidic sugars)
Special components of gram-negative cell walls
- Outer membrane - inner part ( lipopolysasccharides)
Lipopolysaccharides - Lipid A ( endotoxin activity)
- Lipoproteins
-fx: anchor the outer membrane to the peptidoglycan layer and stabilizes the outer membrane
- Periplasmic space
- fluid filled bet. outer and inner plasma membrane
-structure: enzymes; breakdown for destroy of large non-transportable molecules into transportable ones
Acid-fast cell wall
- cell wall: lipid rich ( mycolic acids): wax
-cell wall are hydrophobic, meaning cannot be stained
INTERNAL STRUCTURE
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Mesosomes
invagination of cell wall, for cell division
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Endospheres
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compo: dipicolinic acid and calcium ( dipicolinate)
for resistance: heat, drying, chemical agents and radiation
spore production: sporulation: when environment are detrimental to bacteria
Germination: when enivironment is more favorable
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bacteria
SHAPES
(1) Coccus - spherical or round shaped (staphylococcus, streptococcus)
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(2) Bacili - Rod-shaped (Escherichia coli, Salmonella)
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PROJECTING STRUCTURE
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AXIAL FILAMENTS
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structure: bundles of fibrils
spiral around the cell, create rotating movement
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-Porins - special protein channels, allow passage of small or low MW hydrophilic substances