1 / 32

Bacterial Structures and Cell Wall: Importance and Function

This article explores the different structures found in bacteria, such as capsules, flagella, pili, and cell walls. It discusses their functions, medical significance, and the role of the cell membrane in transport and energy production.

tshane
Download Presentation

Bacterial Structures and Cell Wall: Importance and Function

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Bacterial Structures

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

  3. Filamentous Protein Appendages

  4. Flagella - motility E. coli O157:H7 Rotate like a propeller Proton motive force used for energy Presence/arrangement can be used as an identifying marker

  5. 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)

  6. 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

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

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

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

  10. 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

  11. 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

  12. Cell Wall

  13. 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)

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

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

  16. 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

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

  18. 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

  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

  27. Facilitated Diffusion

  28. Active Transport

  29. Internal structures: Chromosome

  30. Internal structures: Ribosomes

  31. Internal structures:Storage Granules

  32. Internal Structures: Endospores

More Related