vsv1

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vsv1

  1. 1. Dr. Alvin Fox The Bacterial Cell
  2. 2. Key Words Prokaryotic Outer membrane Eubacteria (Bacteria) Periplasmic space Oxidative phosphorylation Eukaryotic Spheroplast/protoplast Plasmid Flagella Chromosome Chemotaxis Ribosome Axial filament Peptidoglycan (murein, mucopeptide) Periplasmic binding protein Gram stain Permeases Gram negative Storage Granules Gram positive Pili (fimbriae) Cell envelope Capsule (slime layer, glycocalyx) Cell membrane Endospore (spore) Cell wall Archaebacteria ( Archaea )
  3. 3. PROKARYOTES BACTERIA ARCHAEA EUKARYOTES
  4. 4. Prokaryotes (Bacteria) <ul><li>Eubacter &quot;True&quot; bacteria </li></ul><ul><ul><li>human pathogens </li></ul></ul><ul><ul><li>clinical or environmental </li></ul></ul><ul><ul><li>one kingdom </li></ul></ul><ul><li>Archaea </li></ul><ul><ul><li>Environmental organisms </li></ul></ul><ul><ul><li>second kingdom </li></ul></ul>
  5. 5. Eukaryotes <ul><li>Other cell-based life e.g. </li></ul><ul><li>plants </li></ul><ul><li>animals </li></ul><ul><li>fungi </li></ul>
  6. 6. Prokaryotic Cell (versus Eukaryotic Cell) <ul><li>Not compartmentalized </li></ul><ul><li>Cell membranes lack sterols (e.g. cholesterol) </li></ul><ul><li>Single circular chromosome </li></ul><ul><li>Ribosomal are 70S </li></ul><ul><ul><li>- subunits </li></ul></ul><ul><ul><ul><li>30S (16S rRNA) </li></ul></ul></ul><ul><ul><ul><li>50S (5S & 23S rRNA) </li></ul></ul></ul>
  7. 7. Bacteria versus Archaebacteria <ul><li>Eubacteria </li></ul><ul><ul><li>peptidoglycan (murein) </li></ul></ul><ul><ul><li>muramic acid </li></ul></ul><ul><li>Archaebacteria </li></ul><ul><ul><li>pseudomurein </li></ul></ul><ul><ul><li>no muramic acid </li></ul></ul><ul><li> </li></ul><ul><li> </li></ul>
  8. 8. Bacteria versus Archaebacteria <ul><li>16S rRNA </li></ul><ul><ul><li>sequence very different </li></ul></ul>
  9. 9. Eukaryotic cell Prokaryotic cell Gram + Gram - Cell wall Cell (inner) membrane Outer membrane Ribosomes Rough endoplasmic reticulum Mitochondria Granule (e.g . animal) Cell wall Nucleoid Nucleus Cell membrane Capsule Cytoplasm Flagellum Pili
  10. 10. Bacteria <ul><li>Plasmids </li></ul><ul><ul><li>Extra-chromosomal DNA </li></ul></ul><ul><ul><li>multiple copy number </li></ul></ul><ul><ul><li>coding pathogenesis and antibiotic </li></ul></ul><ul><ul><li>resistance factors </li></ul></ul><ul><ul><li>bacterial replication </li></ul></ul>
  11. 11. The Cell Envelope Gram Stain Gram Positive Gram Negative
  12. 12. Cytoplasm Oxidative phosphorylation occurs at cell membrane (since there are no mitochondria). Cell membrane <ul><li>The cell wall is outside of cell membrane </li></ul><ul><ul><li>rigid, protecting cell from osmotic lysis. </li></ul></ul>Cell Wall
  13. 13. GRAM POSITIVE GRAM NEGATIVE Cytoplasm Cytoplasm Lipoteichoic acid Peptidoglycan-teichoic acid Cytoplasmic membrane Inner (cytoplasmic) membrane Outer Membrane Lipopolysaccharide Porin Braun lipoprotein Periplasmic space
  14. 14. Outer Membrane <ul><li>Gram negative bacteria </li></ul><ul><li>major permeability barrier </li></ul><ul><li>space between inner and outer membrane </li></ul><ul><ul><li>periplasmic space </li></ul></ul><ul><ul><ul><li>store degradative enzymes </li></ul></ul></ul><ul><li>Gram positive bacteria </li></ul><ul><li>no periplasmic space </li></ul>
  15. 15. GRAM NEGATIVE CELL ENVELOPE Cytoplasm Inner (cytoplasmic) membrane Outer Membrane (Major permeability barrier) Lipopolysaccharide Porin Braun lipoprotein Periplasmic space Degradative enzyme Periplasmic binding protein Permease
  16. 16. GRAM POSITIVE CELL ENVELOPE Cytoplasm Lipoteichoic acid Peptidoglycan-teichoic acid Cytoplasmic membrane Degradative enzyme
  17. 17. FLAGELLA <ul><li>Some bacteria are motile </li></ul><ul><li>Locomotory organelles- flagella </li></ul><ul><li>Taste environment </li></ul><ul><li>Respond to food/poison </li></ul><ul><ul><li>chemotaxis </li></ul></ul>
  18. 18. <ul><li>Flagella </li></ul><ul><ul><li>embedded in cell membrane </li></ul></ul><ul><ul><li>project as strand </li></ul></ul><ul><ul><li>Flagellin (protein) subunits </li></ul></ul><ul><ul><li>move cell by propeller like action </li></ul></ul>
  19. 19. Axial filaments <ul><ul><li>spirochetes </li></ul></ul><ul><ul><li>similar function to flagella </li></ul></ul><ul><ul><li>run lengthwise along cell </li></ul></ul><ul><ul><li>snake-like movement </li></ul></ul>
  20. 20. Making Wall-less forms <ul><li>Result from action of: </li></ul><ul><ul><li>enzymes lytic for cell wall </li></ul></ul><ul><ul><li>antibiotics inhibiting peptidoglycan biosynthesis </li></ul></ul><ul><li>Usually non-viable </li></ul><ul><li>Wall-less bacteria that don’t replicate: </li></ul><ul><ul><li>spheroplasts (with outer membrane) </li></ul></ul><ul><ul><li>protoplasts (no outer membrane). </li></ul></ul><ul><li>Wall-less bacteria that replicate </li></ul><ul><ul><li>L forms </li></ul></ul>
  21. 21. Naturally Wall-less Genus <ul><li>Mycloplasma </li></ul>
  22. 22. Pili (fimbriae) <ul><li>hair-like projections of the cell </li></ul><ul><li>sexual conjugation </li></ul><ul><li>adhesion to host epithelium </li></ul>
  23. 23. Capsules and slime layers <ul><li>outside cell envelope </li></ul><ul><li>well defined: capsule </li></ul><ul><li>not defined: slime layer or glycocalyx </li></ul><ul><li>usually polysaccharide </li></ul><ul><li>often lost during in vitro culture </li></ul><ul><li>protective in vivo </li></ul>
  24. 24. Endospores (spores) <ul><li>Dormant cell </li></ul><ul><li>Produced when starved </li></ul><ul><li>Resistant to adverse conditions </li></ul><ul><li>- high temperatures </li></ul><ul><li>- organic solvents </li></ul><ul><li>contain calcium dipicolinate </li></ul><ul><li>Bacillus and Clostridium </li></ul>

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