1. Prokaryotic Profiles: the Bacteria and the Archaea Chapter 4

2. Prokaryotes The first prokaryotes evolved at least 3.5 billion years ago

4. Prokaryotic Cell Flowchart Prokaryotic Cell Appendages FlagellaPili/Fimbriae Cell Envelope GlycocalyxCell WallCell Membrane Cytoplasm Cell PoolRibosomesGranulesNucleoid/Chromosome

5. flagella 3 parts – filament – long, thin, helical structure composed of proteins – hook- curved sheath – basal body – stack of rings firmly anchored in cell wall rotates 360 o 1-2 or many distributed over entire cell functions in motility One can generalize that all spirilla, about half of the bacilli, and a small number of cocci are flagellated

6. Fig 4.2b

7. Flagellar arrangements 1. monotrichous – single flagellum at one end 2. lophotrichous – small bunches arising from one end of cell 3. amphitrichous – flagella at both ends of cell 4. peritrichous – flagella dispersed over surface of cell, slowest

8. Fig. 4.4

9. monotrichous lophotrichous amphitrichous peritrichous

10. Chemotaxis Positive chemotaxis- movement toward a favorable stimulus; runs Negative chemotaxis- movement away from a repellant; tumbles Phototaxis- movement in response to light Receptors in the cell membrane bind to molecules in the extracellular environment and send signals to the flagella

11. Fig 4.5 counterclockwise clockwise

12. Fig 4.6 Chemotaxis

13. axial filaments periplasmic, internal flagella, enclosed between cell wall and cell membrane of spirochetes motility

14. Fig 4.7a b

15. fimbrae fine hairlike bristles from the cell surface function in adhesion to other cells and surfaces

16. pili rigid tubular structure made of pilin protein found only in Gram negative cells Functions – joins bacterial cells for DNA transfer (conjugation) – adhesion

17. Conjugation

18. glycocalyx Coating of molecules external to the cell wall, made of sugars and/or proteins 2 types 1. capsule - highly organized, tightly attached 1. Streptococcus pneumonia, Haemophilus influenzae 2. slime layer - loosely organized and attached functions – attachment – inhibits killing by white blood cells – receptor

19. Fig 4.10

20. 2 Types of Glycocalyx

21. Biofilms

22. 4 groups based on cell wall composition 1. Gram positive cells 2. Gram negative cells 3. Bacteria without cell walls 4. Bacteria with chemically unique cell walls

23. Peptidoglycan unique macromolecule composed of a repeating framework of long glycan chains cross-linked by short peptide fragments provides strong, flexible support to keep bacteria from bursting or collapsing because of changes in osmotic pressure

25. Fig. 4.14c

26. Gram positive cell wall Consists of – a thick, homogenous sheath of peptidoglycan 20- 80 nm thick – tightly bound acidic polysaccharides, including teichoic acid and lipoteichoic acid – cell membrane Retain crystal violet and stain purple

27. Gram positive wall

28. Gram negative cell wall Consists of – an outer membrane containing lipopolysaccharide (LPS) – thin shell of peptidoglycan – periplasmic space – inner membrane Lose crystal violet and stain red from safranin counterstain

29. Gram negative cell wall

30. Gram positiveGram negative Fig 4.16

32. Nontypical cell walls Mycobacterium and Nocardia contain mycolic acid in their cell walls; stain acid fast Archaea lack peptidoglycan; mainly composed of polysaccharides or lack a cell wall Mycoplasmas lack cell walls

33. L forms Loss of the cell wall due to mutation or chemicals lead to L forms of gram positive and negative bacteria

34. Fig. 4.17

36. Cell Membrane Structure Mesosomes- invagination or artifacts of the cell membrane; may be involved in cell wall synthesis Phospholipid bilayer

37. Cell Membrane Functions Regulates transport Selectively permeable Secretion Metabolic reactions

38. Cytoplasm dense gelatinous solution of sugars, amino acids, & salts 70-80% water serves as solvent for materials used in all cell functions DNA plasmids

39. Chromosome single, circular, double-stranded DNA molecule that contains all the genetic information required by a cell DNA is tightly coiled around a protein, aggregated in a dense area called the nucleoid

40. plasmids small circular, double-stranded DNA free or integrated into the chromosome duplicated and passed on to offspring not essential to bacterial growth & metabolism may encode antibiotic resistance, tolerance to toxic metals, enzymes & toxins used in genetic engineering- readily manipulated & transferred from cell to cell

41. ribosomes made of 60% ribosomal RNA & 40% protein consist of 2 subunits: large & small procaryotic differ from eucaryotic ribosomes in size & number of proteins site of protein synthesis All cells have ribosomes.

42. ribosomes

43. Inclusions, granules intracellular storage bodies vary in size, number & content bacterial cell can use them when environmental sources are depleted Examples: glycogen, poly-  -hydroxybutyrate, gas vesicles for floating, sulfur and polyphosphate granules, magnetosomes

44. Inclusions

45. Endospores Resting, dormant cells produced by some G+ genera: Clostridium, Bacillus & Sporosarcina Have a 2-phase life cycle – vegetative cell & an endospore sporulation -formation of endospores germination- return to vegetative growth

46. Endospores hardiest of all life forms withstand extremes in heat, drying, freezing, radiation & chemicals not a means of reproduction resistance linked to high levels of calcium & dipicolinic acid dehydrated, metabolically inactive thick coat longevity verges on immortality 25, 250 million years. pressurized steam at 120 o C for 20-30 minutes will destroy.

47. Table 4.2

48. Endospores

49. 3 shapes of bacteria cocci - spherical bacilli - rod spiral - helical, comma, twisted rod, spirochete

51. Fig. 4.25

52. Table 4.3

53. Fig. 4.23 spirochete spirillumCoccus in chains Diplobacillus arrangement

54. Fig. 4.26

55. Methods in bacterial identification 1. Microscopic morphology 2. Macroscopic morphology – colony appearance 3. Physiological / biochemical characteristics 4. Chemical analysis 5. Serological analysis 6. Genetic & molecular analysis G + C base composition DNA analysis using genetic probes Nucleic acid sequencing & rRNA analysis

56. species –a collection of bacterial cells which share an overall similar pattern of traits in contrast to other bacteria whose pattern differs significantly strain or variety – a culture derived from a single parent that differs in structure or metabolism from other cultures of that species (biovars, morphovars) type – a subspecies that can show differences in antigenic makeup (serotype or serovar), susceptibility to bacterial viruses (phage type) and in pathogenicity (pathotype).

57. Major Taxonomic Groups of Bacteria per Bergey’s manual Gracilicutes – gram-negative cell walls, thin- skinned Firmicutes – gram-positive cell walls, thick skinned Tenericutes – lack a cell wall & are soft Mendosicutes – archaea, primitive procaryotes with unusual cell walls & nutritional habits

58. Unusual Forms of Medically Significant Bacteria Rickettsias – small, gram negative, – obligate intracellular parasite – arthropod vector Clamydias – small, gram negative – obligate intracellular parasite Mycoplasms – small – lack cell walls

59. Free Living Nonpathogenic Bacteria Photosynthetic Bacteria – Cyanobacteria- gram negative – Green and Purple Sulfur Bacteria – Gliding, Fruiting Bacteria- gram negative – Appendaged Bacteria- attach to surfaces

60. Fig. 4.35

61. Swarm and stalked phases

62. Table 4.6a

63. Table 4.6b

64. Archaea: the other procaryotes constitute third Domain Archaea seem more closely related to Domain Eukarya than to bacteria contain unique genetic sequences in their rRNA have unique membrane lipids & cell wall construction live in the most extreme habitats in nature, extremophiles adapted to heat salt acid pH, pressure & atmosphere includes: methane producers, hyperthermophiles, extreme halophiles, and sulfur reducers

65. Table 4.7