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Bacteria I

Bacteria I. General Nature. 1) Prokaryotic 2) Single celled (some say multicellular) 3) Microscopic in size 4) Cell Wall usually present (varies, but contains contains carbohydrate called _____________. Typical Bacterial Cell (Prokaryotic). Bacterial Colonies growing on Agar plates.

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Bacteria I

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  1. Bacteria I

  2. General Nature • 1) Prokaryotic • 2) Single celled (some say multicellular) • 3) Microscopic in size • 4) Cell Wall usually present (varies, but contains contains carbohydrate called _____________

  3. Typical Bacterial Cell (Prokaryotic)

  4. Bacterial Colonies growing on Agar plates

  5. Common Shapes of Bacteria • Spherical: cocci (s. coccus) • single cells • pairs = diplococci • 4’s = tetrads • 8’s = sarcinae • chains = streptococci • grape-like clusters = staphylococci

  6. More shapes

  7. Rod Shaped • Bacillus (Rod shaped) Bacillus anthracis

  8. More common shapes • Spiral = Spirilla(singular=spirillum) • Spirochetes: long spirilla with many tight coils

  9. Typical spirillum

  10. spirochetes

  11. some bacteria are genetically ____________ which means the cells can have many shapes.

  12. Corynebacteriumdiphtheriae • Pleomorphic species

  13. Prokaryotic Cell Structure • 1) Glycocalyx (sugar coat) If firmly attached called a Capsule If loosely attached called a slime layer

  14. Bacterial Capsule/Slime Layer • Function: protect cell from drying, chemicals, host body defenses; also helps for attachment to host cells. • Increases virulence in pathogenic species • Special capsule stain allows us to view.

  15. Biofilms • Slimy layers of bacteria formed by capsules • Form on teeth, contact lenses, IUDs, in lungs, ear infections, other infections, shower door scum etc. • Protect bacteria from drugs and body defense, 641 in text! • Life cycle of a biofilm: Essay….

  16. Life cycle of a biofilm, continued

  17. Life cycle of a biofilm, concluded

  18. 99% of bacteria grow in biofilms (can be 100s of cells thick)! • Antibiotics, antibodies & phagocytes have difficulty penetrating • Can be 1500x more resistant! • And……..Biofilms MOVE!

  19. Parts of the Bacterial Cell: 2) Flagella • long, whip-like structures for motility (movement) • location is important in identifying unknowns • Monotrichous: one flagellum (single polar flagellum) • Amphitrichous: flagella at each end of cell • Lophotrichous: 2 or more flagella at one end of cell • Peritrichous: flagella all over the cell • Atrichous (without flagella) • too thin to see with light microscope • to view, thicken with flagella stain or use electron microscope

  20. Types of Flagella arrangements

  21. How Flagella Work

  22. 3)__________ filaments • similar to flagella, but under outer membrane (sheath) of gram negative cell wall (endoflagella) • in spirochetes only • provide drilling motion (figure 4.10)

  23. 4) ___________ • Short, finger-like projections for attachment • Important for virulence

  24. 5) Parts of the Bacterial Cell: Pili (pilus) • Longer than fimbriae • Usually 1 or 2 per cell • Some pili used by bacteria in a mating process to exchange DNA • Sometimes called conjugation (sex) pili • Motility now associated with pili • Twitching • Gliding

  25. Bacteria II • 6) Cell Wall

  26. Parts of the Bacterial Cell • Cell wall : a thick, tough layer forming the shape of the cell • function: protection • Structurally different in gram + versus gram - bacteria

  27. Parts of the Bacterial Cell • The gram positive cell wall: • one thick layer of _______________ (sugars and amino acids bonded into one macromolecule; a very tough material)

  28. Gram negative cell wall • The gram negative cell wall: • two layers • thin inner layer of peptidoglycan • thicker outer membrane of protein and fat

  29. Why should we know gram + & - ? • Why is it important to know if a bacterial pathogen is gram positive or negative? • one of the important characteristics when identifying the bacterium • one of the important characteristics when choosing the best control method...: !

  30. The gram stain • primary stain: crystal violet • all bacteria stain violet • _________ (agent that fixes the stain into the cells): aqueous iodine solution • cells become darker violet

  31. gram stain, continued • decolorization: alcohol (95% ethanol) or an acetone/alcohol blend • only the gram negative cells decolorize • gram positive remain violet • Counterstain:____________ • gram negative cells stain red • gram positive remain violet • (Purple = Postive!)

  32. steps ingram stain What would you see at this point!?

  33. Figure 3.12

  34. items as seen in gram stain

  35. 7) Plasma Membrane

  36. Plasma membrane • cytoplasmic (plasma) membrane • also called cell membrane • ultra-thin layer of fat and protein

  37. phospholipids Polar “Head” = Hydrophillic NonPolar “Tails” = Hydrophobic

  38. detail of “_________________”of plasma membrane • a living, functioning part of the cell • ______________________(selective permeability)

  39. Cell Membrane

  40. plasma membrane • a vulnerable part of the cell • easy to damage with heat or chemicals

  41. Solution Solute Solvent (usually water)

  42. Cell Membrane

  43. Things Can/Cannot go through: *Can Go Through: • Small, uncharged molecules (CO2, O2) • Small, polar molecules (H2O) • Large non polar molecules (Steroids)

  44. Transport • Passive – Does not require energy • Dialysis • Simple Diffusion • Osmosis • Facilitated • Active – Requires Energy (Na+/K+ Pump)

  45. Other things attached a Cell Membrane

  46. 8) ____________ • The cytoplasm (cell fluid) • semi-liquid contents of the cell • complex mixture of chemicals • water • protein • many other chemicals • forms a colloidal system • two states, sol and gel

  47. Cytoplasm: a colloidal system • ___: water continuous ____: protein continous vulnerability: can permanently convert sol to gel with heat or chemicals

  48. 8A Stuff in the cytoplasm: Ribosomes • ribosomes: bodies within the cytoplasm that function in protein synthesis • Composed of 2 subunits = 70 S (prokaryotic size) • S=Svedberg units of sedimentation with centrifugation • Consists of protein and ribosomal RNA (rRNA)

  49. 8B. ___________ • inclusion bodies: store nutrients (starch, glycogen, fats) for later use during periods of starvation • Could store iron oxide or phosphate depending on cell.

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