Chapter 4

1. Chapter 4 Functional Anatomy of Prokaryotic

2. Prokaryotic Cells • Comparing Prokaryotic and Eukaryotic Cells • Prokaryote comes from the Greek words for prenucleus. • Eukaryote comes from the Greek words for true nucleus.

3. Prokaryote Eukaryote • Paired chromosomes, in nuclear membrane • Histones • Organelles • Polysaccharide cell walls • Mitotic spindle • One circular chromosome, not in a membrane • No histones • No organelles • Peptidoglycan cell walls • Binary fission

7. Unusual shapes • Star-shaped Stella • Square Haloarcula Figure 4.5

9. Sterptococcus pneumoniae • Diplococci • Gram positive • Cause pneumonia disease

10. Staphylococcus aureus • Gram positive • Normal microbiota on skin • aureus = golden colony

11. Streptococcus pyogenes • Gram positive bacteria • Cocci • Cause strep throat , Tonsillitis and Impetigo

12. Bacillus anthracis • Gram positive • Spore forming • Bacilli • Cause Anthrax disease

13. Salmonella typhi • Gram negative • Bacilli • Flagellated • Cause typhoid fever

14. Clostridium botulinum • Gram positive • Bacilli • Spore forming • Cause Food borne botulism

15. Vibrio cholerae • Gram negative • Comma shaped • Flagellated • Cause cholera disease

16. Helicobacter pylori • Gram negative • Helix shaped • Cause gastric ulcer

17. Treponema pallidum • Helically coiled microorganism • Cause syphilis disease

18. Most bacteria are monomorphic • A few are pleomorphic

19. The shape of a bacterium is determined by heredity. • Genetically, most bacteria are monomorphic that is, they maintain a single shape. • However, a number of environmental conditions can alter that shape.

20. If the shape is altered, identification becomes difficult. • Some bacteria, such as Rhizobium and Corynebacterium are genetically pleomorphic, which means they can have many shapes, not just one.

21. Arrangements • Pairs: diplococci, diplobacilli • Clusters: staphylococci • Chains: streptococci, streptobacilli

22. Glycocalyx • Outside cell wall • Usually sticky • A capsule is neatly organized • A slime layer is unorganized & loose • Extracellular polysaccharide allows cell to attach • Capsules prevent phagocytosis Figure 4.6a, b

23. Flagella • Outside cell wall • Made of chains of flagellin • Attached to a protein hook • Anchored to the cell wall and cell membrane by the basal body Figure 4.8

24. Flagella Arrangement Figure 4.7

25. Figure 4.8

26. Motile Cells • Rotate flagella to run or tumble • Move toward or away from stimuli (taxis) • Flagella proteins are H antigens (e.g., E. coli O157:H7)

27. Motile Cells Figure 4.9

28. Axial Filaments • Endoflagella • In spirochetes • Anchored at one end of a cell • Rotation causes cell to move Figure 4.10a

29. Fimbriae and Pili • Fimbriae allow attachment • Pili are used to transfer DNA from one cell to another

30. Cell Wall • Prevents osmotic lysis • Made of peptidoglycan (in bacteria) Figure 4.6a, b

31. Peptidoglycan • Polymer of disaccharideN-acetylglucosamine (NAG) & N-acetylmuramic acid (NAM) • Linked by polypeptides Figure 4.13a

32. Figure 4.13b, c

33. Gram-positive cell walls Gram-negative cell walls • Thick peptidoglycan • Teichoic acids • In acid-fast cells, contains mycolic acid • Thin peptidoglycan • No teichoic acids • Outer membrane

34. Gram-Positive cell walls • Teichoic acids: • Lipoteichoic acid links to plasma membrane • Wall teichoic acid links to peptidoglycan • May regulate movement of cations • Polysaccharides provide antigenic variation Figure 4.13b

36. Gram-Negative Outer Membrane • Lipopolysaccharides, lipoproteins, phospholipids. • Forms the periplasm between the outer membrane and the plasma membrane. • Protection from phagocytes, complement, antibiotics. • O polysaccharide antigen, e.g., E. coli O157:H7. • Lipid A is an endotoxin. • Porins (proteins) form channels through membrane

37. Gram-Negative Outer Membrane Figure 4.13c

38. Gram Stain Mechanism • Crystal violet-iodine crystals form in cell • Gram-positive • Alcohol dehydrates peptidoglycan • CV-I crystals do not leave • Gram-negative • Alcohol dissolves outer membrane and leaves holes in peptidoglycan • CV-I washes out

39. Atypical Cell Walls • Mycoplasmas • Lack cell walls • Sterols in plasma membrane • Archaea • Wall-less, or • Walls of pseudomurein (lack NAM and D amino acids)

40. Damage to Cell Walls • Lysozyme digests disaccharide in peptidoglycan. • Penicillin inhibits peptide bridges in peptidoglycan. • Protoplast is a wall-less cell( completely or partially removed). • Spheroplast is a cell from which the cell wall has been almost completely removed.

41. Damage to Cell Walls • L forms or cell wall deficient bacteria (CWD) are wall-less cells that swell into irregular shapes such as Mycoplasma . • Protoplasts and spheroplasts are susceptible to osmotic lysis.

42. Plasma Membrane Figure 4.14a

43. Plasma Membrane • Phospholipid bilayer • Peripheral proteins • Integral proteins • Transmembrane proteins Figure 4.14b

44. Fluid Mosaic Model • Membrane is as viscous as olive oil. • Proteins move to function • Phospholipids rotate and move laterally Figure 4.14b

45. Plasma Membrane • Selective permeability allows passage of some molecules • Enzymes for ATP production • Photosynthetic pigments on foldings called chromatophores or thylakoids

46. Plasma Membrane • Damage to the membrane by alcohols, quaternary ammonium (detergents) and polymyxin antibiotics causes leakage of cell contents.

47. Movement Across Membranes • Simple diffusion: Movement of a solute from an area of high concentration to an area of low concentration. • Facilitative diffusion: Solute combines with a transporter protein in the membrane.

48. Movement Across Membranes Figure 4.17

49. Movement Across Membranes • Osmosis • Movement of water across a selectively permeable membrane from an area of high water concentration to an area of lower water. • Osmotic pressure • The pressure needed to stop the movement of water across the membrane. Figure 4.18a

50. Figure 4.18c-e