Dr. Alvin Fox
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Prokaryotic Outer membrane
Eubacteria ( Bacteria ) Periplasmic space
Archaebacteria ( Archaea ) Oxidative phosphorylation
Eukaryotic
Plasmid
Chromosome
Ribosome
Spheroplast/protoplast
Flagella
Chemotaxis
Axial filament
Peptidoglycan (murein, mucopeptide) Periplasmic binding protein
Gram stain Permeases
Gram negative Storage Granules
Gram positive
Cell envelope
Pili (fimbriae)
Capsule (slime layer, glycocalyx)
Cell membrane Endospore (spore)
Cell wall
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PROKARYOTES
BACTERIA ARCHAEA
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•
Eubacter "True" bacteria
– human pathogens
– clinical or environmental
– one kingdom
•
Archaea
–
Environmental organisms
– second kingdom
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•
Other cell-based life e.g.
– plants
– animals
– fungi
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Prokaryotic Cell (versus Eukaryotic
Cell)
• Not compartmentalized
•
Cell membranes lack sterols (e.g. cholesterol)
• Single circular chromosome
•
Ribosomes
- 70S
- subunits
• 30S (16S rRNA)
•
50S (5S & 23S rRNA)
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• Eubacteria
– peptidoglycan (murein)
– muramic acid
•
Archaebacteria
– pseudomurein
– no muramic acid
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•
16S rRNA
– sequence different
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Eukaryotic cell Prokaryotic cell
(e.g
. animal) Gram +
Nucleoid
Cell membrane
Flagellum
Cell wall Rough endoplasmic reticulum
Nucleus
Pili
Gram -
Cytoplasm
Mitochondria
Granule
Capsule
Cell (inner) membrane
Ribosomes
Outer membrane
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Cell wall

•
Extra-chromosomal DNA
• multiple copy number
• coding
pathogenesis factors
- antibiotic resistance factors
• bacterial replication
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Gram Positive Gram Negative
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Oxidative phosphorylation occurs at cell membrane
(since there are no mitochondria).
Cell Wall
Cytoplasm
Cell membrane
The cell wall is outside of cell membrane
– rigid, protecting cell from osmotic lysis.
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GRAM POSITIVE
Lipoteichoic acid Peptidoglycan-teichoic acid
Cytoplasmic membrane
Cytoplasm
GRAM NEGATIVE
Porin
Lipopolysaccharide
Outer Membrane
Braun lipoprotein
Inner (cytoplasmic) membrane
Cytoplasm
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Outer Membrane
Gram negative bacteria
• major permeability barrier
• space between inner and outer membrane
– periplasmic space
 store degradative enzymes
•
Gram positive bacteria
• no periplasmic space
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GRAM NEGATIVE
CELL ENVELOPE
Outer Membrane
(Major permeability barrier)
Porin
Lipopolysaccharide
Braun lipoprotein
Degradative enzyme
Inner (cytoplasmic) membrane
Periplasmic binding protein
Permease
Cytoplasm 15

GRAM POSITIVE
CELL ENVELOPE
Degradative enzyme
Lipoteichoic acid
Peptidoglycan-teichoic acid
Cytoplasmic membrane
Cytoplasm
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• Some bacteria are motile
•
Locomotory organelles- flagella
•
Taste environment
•
Respond to food/poison
– chemotaxis
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•
Flagella
– embedded in cell membrane
– project as strand
–
Flagellin (protein) subunits
– move cell by propeller like action
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– spirochetes
– similar function to flagella
– run lengthwise along cell
– snake-like movement
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• Result from action of:
– enzymes lytic for cell wall
– antibiotics inhibiting peptidoglycan biosynthesis
• Usually non-viable
•
Wall-less bacteria that don’t replicate:
– spheroplasts (with outer membrane)
– protoplasts (no outer membrane).
•
Wall-less bacteria that replicate
–
L forms
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Naturally Wall-less Genus
•
Mycoplasma
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• hair-like projections of the cell
• sexual conjugation
• adhesion to host epithelium
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• outside cell envelope
• well defined: capsule
• not defined: slime layer or glycocalyx
• usually polysaccharide
• often lost during in vitro culture
• protective in vivo
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•
Dormant cell
•
Produced when starved
•
Resistant to adverse conditions
- high temperatures
- organic solvents
• contain calcium dipicolinate
•
Bacillus and Clostridium
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