Morphology of Prokaryotic Cells: Cell Shapes

1. Morphology of Prokaryotic Cells: Cell Shapes

2. Morphology of Prokaryotic Cells: terminology in practice • Curved rods: • Campylobacter species • Vibrio species • Spiral rods: • Helicobacter species • Spirillum species • Spirochetes: • Leptospirosa species

3. Morphology of Prokaryotic Cells: Cell Groupings

4. **Bacterial Structures** You should know what all of the structures on this diagram are - what their basic composition is and what their function is

5. The Glycocalyx: Capsules and Slime Layers • Outermost layer • Polysaccharide or polypeptide • May allow cells to adhere to a surface • Contributes to bacterial virulence by preventing phagocytosis • An important virulence factor

6. Filamentous Protein Appendages Escherichia coli Enterococcusfaecium

7. 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

8. Flagella - motility Rotate like a propeller Proton motive force used for energy Chemotaxis - Directed movement towards/away from a chemical Presence/arrangement can be used as an identifying marker • Peritrichous • Polar • Other (ex. tuft on both ends)

9. Pili - attachment Common pili (fimbriae); singular = pilus Function in adhesion = virulence factor Helical arrangement of protein subunits Sex pili - Conjugation Sharing of mobile genetic information – plasmids

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

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 glycanchains • Glycan chains are connected to each other via peptide chains on NAM molecules Know the basic structure/composition of the bacterial cell wall; know the structureal and chemical differences between the cell walls of Gram-negative and Gram-positive bacteria and how these differences relate to how they appear in a Gram stained slide

13. Cell Wall

14. Cell Wall • 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 • Lipopolysaccharide(LPS) O antigen Core polysaccharide Lipid A

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. The Gram stain

21. Acid fast stains:Fite’s, modified Fite’s, Kinyoun Primary stain: carbolfuchsin Decolorizing agent: acid alcohol Secondary stain: methylene blue

22. 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

23. 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

24. 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

25. 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

26. 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

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

28. Facilitated Diffusion

29. Diffusion of water is Osmosis

30. Active transport: Proton Motive Force

31. Active transport: Use ATP

32. Active transport: Group translocation

33. Internal structures: Chromosome

34. Internal structures: Ribosomes

35. Internal structures:Storage Granules

36. Internal structures: Cytoskeleton

37. Internal structures: Endospores