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Bacterial Structures

Bacterial Structures. Definitions. Poly = Many, Mono = 1, Di = 2, Tri = 3. Polysaccharide Lipid/phospholipid Non-polar, hydrophobic molecule comprising the cell membrane ATP (Adenosine Triphosphate) The energy containing molecule. Sugar. Bacterial Structures. Capsule or Glycocalyx.

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Bacterial Structures

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  1. Bacterial Structures

  2. Definitions Poly = Many, Mono = 1, Di = 2, Tri = 3 • Polysaccharide • Lipid/phospholipid • Non-polar, hydrophobic molecule comprising the cell membrane • ATP (Adenosine Triphosphate) • The energy containing molecule Sugar

  3. Bacterial Structures

  4. Capsule or Glycocalyx • Outermost layer • Polysaccharide or polypeptide • Allows cells to adhere to a surface • Contributes to bacterial virulence-avoid phagocytosis

  5. Filamentous Protein Appendages

  6. Flagella - motility Rotate like a propeller Proton motive force used for energy Presence/arrangement can be used as an identifying marker

  7. Flagella - motility Rotate like a propeller Proton motive force used for energy Presence/arrangement can be used as an identifying marker Peritrichous Polar Other (ex. tuft on both ends)

  8. Cell movement is due to a series of “runs” and “tumbles” Flagella - motility Chemotaxis - Directed movement towards/away from a chemical • “Runs” are longer when cell is going in the right direction https://www.youtube.com/watch?v=EpC6G_DGqkI

  9. Different types of pili Common pili (fimbriae) Sex pili - Conjugation

  10. Cell Wall Provides rigidity to the cell • Protection against osmotic forces • Bursting from massive influx of water

  11. Cell Wall Provides rigidity to the cell (prevents it from bursting)

  12. Cell Wall • Peptidoglycan - rigid molecule; unique to bacteria • Alternating subunits of NAG and NAM form glycan chains • Glycan chains are connected to each other via peptide chains on NAM molecules

  13. Cell Wall

  14. Cell Wall • Peptidoglycan - rigid molecule; unique to bacteria • Alternating subunits of NAG and NAM form glycan chains • Glycan chains are connected to each other via peptide chains on NAM molecules Medical significance of peptidoglycan • Target for selective toxicity; synthesis is targeted by certain antimicrobial medications (penicillins, cephalosporins) • Recognized by innate immune system • Target of lysozyme (in egg whites, tears)

  15. Cell Wall Gram-positive Thick layer of peptidoglycan Teichoic acids

  16. Cell WallGram-negative Thin layer of peptidoglycan Outer membrane - additional membrane barrier; porins permit passage lipopolysaccharide (LPS)

  17. Cell WallGram-negative Thin layer of peptidoglycan Outer membrane - additional membrane barrier; porins permit passage lipopolysaccharide (LPS) - ex. E. coli O157:H7 endotoxin - recognized by innate immune system

  18. Cell WallGram-negative Thin layer of peptidoglycan Outer membrane - additional membrane barrier; porins permit passage lipopolysaccharide (LPS) periplasm

  19. Cytoplasmic membrane • Defines the boundary of the cell • Semi-permeable; excludes all but water, gases, and some small hydrophobic molecules • Transport proteins function as selective gates (selectively permeable) • Control entrance/expulsion of antimicrobial drugs • Receptors provide a sensor system • Phospholipid bilayer, embedded with proteins

  20. Cytoplasmic membrane • Defines the boundary of the cell • Semi-permeable; excludes all but water, gases, and some small hydrophobic molecules • Transport proteins function as selective gates (selectively permeable) • Control entrance/expulsion of antimicrobial drugs • Receptors provide a sensor system • Phospholipid bilayer, embedded with proteins

  21. Cytoplasmic membrane • Defines the boundary of the cell • Semi-permeable; excludes all but water, gases, and some small hydrophobic molecules • Transport proteins function as selective gates (selectively permeable) • Control entrance/expulsion of antimicrobial drugs • Receptors provide a sensor system • Phospholipid bilayer, embedded with proteins • Fluid mosaic model

  22. Cytoplasmic membrane Electron transport chain Electron transport chain - Series of proteins that eject protons from the cell, creating an electrochemical gradient Proton motive force is used to fuel: • Synthesis of ATP (the cell’s energy currency) • Rotation of flagella (motility) • One form of transport

  23. If a function of the cell membrane is transport….. • How is material transported in/out of the cell? • Passive transport • No ATP • Along concentration gradient • Active transport • Requires ATP • Against concentration gradient

  24. Types of transport • Passive transport • Simple diffusion • Facilitated diffusion • Osmosis • Active transport • System that uses proton motive force • System that uses ATP • Group translocation

  25. Permeability of the membrane

  26. Osmosis http://www.dnatube.com/video/2775/Onion-Cells-Plasmolysis

  27. Facilitated Diffusion https://www.youtube.com/watch?v=I4123hUU8xo

  28. Active Transport

  29. Internal structures: Chromosome

  30. Internal structures: Ribosomes https://www.youtube.com/watch?v=hEtONGf4Z0A

  31. Internal structures:Storage Granules

  32. Internal Structures: Endospores

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