Bacterial Morphology Arrangement

1. Bacterial Morphology Arrangement

2. Robert Hooke (1635-1703) • English Scientist • First to use the microscope to observe cells • Coined the term “cell”

3. Anton van Leeuwenhoek1632-1723 • Dutch scientist • Invented the first compound microscope • First to observe LIVING cells • Blood cells and protists

4. Robert Brown1773-1858 • Scottish botanist • In 1831 he was the first person to observe the nucleus of a cell

5. Schleiden & Schwann1804-1881 1810-1882

6. Schleiden Said “all plants are made up of cells” Schwann Said “all animals are made up of cells” Developing Cell Theory 1838

7. Cell Theory Overview • All organisms are made of one or more cells [Unicellular or Multicellular]. • All cells carry on life activities. • New cells arise only from other living cells.

8. PROKARYOTIC Simplest form Lack membrane bound structures Lack true nucleus Example: bacteria and cyanobacteria EUKARYOTIC Most common Possess membrane bound structures and a nucleus Found in most living things Prokaryotic vs Eukaryotic

9. Sizes of Cells • Eukaryotic are usually larger than prokaryotic • Both nutrients and wastes are constantly entering and exiting cells • Vary in size and shape

10. Size relationships among prokaryotes

11. Bacterial Morphology Arrangement 1. Rod or Bacilli a.Streptobacilli b. Bacilli 2. Cocci a. Cocci b. Diplococci ( e.g. Neisseria meningitidis) c. Streptococci ( e.g. Streptococcus pyogenes) d. Staphylococci (e.g. Staphylococcus aureus) e. Sarcina f. tetrads ( Micrococcus species)

12. Bacterial Shapes, Arrangements, and Sizes Variety in shape, size, and arrangement but typically described by one of three basic shapes: coccus - spherical bacillus – rod coccobacillus – very short and plump ( Brucella abortus) Streptobacilli ( Bacillus subtilus) diplobacilli spirillum - helical, comma, twisted rod, spirochete – spring-like- flexible ( Treponema pallidum) vibrio – gently curved ( Vibrio cholera) Spirilla- rigid ( Borrelia species) Pleomorphic : variable in shape ( Corynebacterium) 12

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14. Bacterial Shapes, Arrangements, and Sizes Arrangement of cells is dependent on pattern of division and how cells remain attached after division: cocci: singles diplococci – in pairs tetrads – groups of four irregular clusters chains cubical packets bacilli: chains palisades 14

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16. Streptococcus sp.

17. Bacterial morphologies (1)

18. Bacterial morphologies (2)

19. Bacterial morphologies (3)

20. Bacterial Morphology Arrangement 3 Spirl a. Vibrio b. Spirillum c. Spirochete

22. Bacterial morphologies (4)

23. Borrelia (spirochete)

24. Bacterial Cell Structures & Functions Pili

25. Bacterial Cell Structure • Appendages - flagella, pili or fimbriae • Surface layers - capsule, cell wall, cell membrane • Cytoplasm - nuclear material, ribosome, mesosome, inclusions etc. • Special structure - endospore

26. Appendages 1. flagella Some rods and spiral form have this. a). function: motility b). origin : cell membrane flagella attach to the cell by hook and basal body which consists of set(s) of rings and rods Gram - : 2 sets of ring and rods, L, P, S, M rings and rods . e.g. E. coli Gram + : S, M rings and rods .e.g. B. megaterium

27. Flagella • Motility - movement • Swarming occurs with some bacteria • Spread across Petri Dish • Proteus species most evident • Arrangement basis for classification • Monotrichous; 1 flagella • Lophotrichous; tuft at one end • Kophotrichous; tuft at both ends • Amphitrichous; both ends • Peritrichous; all around bacteria

29. Structure of the flagellum

30. c).Origin (continued) • The structure of the bacterial flagella allows it to spin like a propeller and thereby propel the bacterial cell; clockwise or counter clockwise wave like motion. • Bacterial flagella provides the bacterium with mechanism for swimming toward or away from chemical stimuli, a behavior is knows as CHEMOTAXIX, chemosenors in the cell envelope can detect certain chemicals and signal the flagella to respond. d). structure protein in nature: subunit flagellin ( globular protein)

31. Flagella movement(1)

32. Flagella movement(2)

33. 2. Fimbriae and Pili Fimbriae: Shorter than flagella and straighter , smaller, hairlike appendages . Only on some gram- bacteria. a). function: adhere. Not involve in motility. One of the invasive mechanism on bacteria. Some pathogens cause diseases due to this (Antigenic characteristic). Prevent phagocytosis.

34. pili - sex factor. If they make pili, they are + or donors of F factor. It is necessary for bacterial conjugation resulting in the transfer of DNA from one cell to another. It have been implicated in the ability of bacteria to recognize specific receptor sites on the host cell membrane.

35. Conjugation in E. coli

36. b). Origin: Cell membrane c). Position: common pili , numerous over the cell, usually called sex pile, 1-4/cell d). Structure: composed of proteins which can be dissociated into smaller unit Pilin . It belongs to a class of protein Lectin which bond to cell surface polysaccharide.

37. II. CELL SURFACE LAYER 1. Glycocalyx: Capsule or slime layer Many bacteria are able to secrete material that adheres to the bacterial cell but is actually external to the cell. It consists of polypeptide and polysaccharide on bacilli. Most of them have only polysaccharide. It is a protective layer that resists host phagocytosis. Medically important ( Streptococcus pneumonia).

38. Capsule and Slime layer • The layer is well organized and not easily washed off, it is capsule • Slime layer, unorganized material that is easily removed. • They give mucoid growth on agar plate • B. anthracis has a capsule of poly-D-glutamic acid, while S. pyogenes made of Hyaluronic acid. • Function: Resistant phagocytosis, Protect against desiccation, Attachment to surface of solid objects.

39. Axial Filaments • Present in spirochetes ( Treponema pallidum cause syphilis) • Function is motility – gliding motility • Bundles of fibrils that arise at the ends of the cell

40. Axial filament Structurally similar to flagella Unique location under an outer membrane Spirochetes

41. 2. Bacterial Cell Wall General structure: mucopolysaccharide i.e. peptidoglycan. It is made by N-acetylglucosamine and N-acetylmuramic acid. tetrapeptide ( L-alanine- isoglutamine-lysine-alanine) is attached. The entire cell wall structure is cross linked by covalent bonds. This provide the rigidity necessary to maintain the integrity of the cell. N-acetylmuramic acid is unique to prokaryotic cell.

42. Cell walls of bacteria(2)

43. Cell walls of bacteria(3)

44. Cell walls of bacteria(4)

45. Cell walls of bacteria(1)

46. Structure of peptidoglycan(1)

47. Structure of peptidoglycan(2)

48. a). Gram positive bacterial cell wall Thick peptidoglycan layer pentaglycin cross linkage. Teichoic acid (TA): Polymer of ribitol & glycerol joined by phosphate groups Some have peptioglycan teichoic acid. All have lipoteichoic acid.

49. Function of Teichoic acids: * Antigenic determinant * Participate in the supply of Mg to the cell by binding Mg++ * regulate normal cell division. For most part, protein is not found as a constituent of the G+ cell wall except M protein on group streptococci

50. Structure of the Gram-positive Cell Wall