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Fig. 4.1

Bacterial Cell Structure. Fig. 4.1. Cytoplasm. dense gelatinous solution of sugars, amino acids, & salts 70-80% water serves as solvent for materials used in all cell functions. Chromosome.

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Fig. 4.1

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  1. Bacterial Cell Structure Fig. 4.1

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

  3. 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

  4. DNA temperature melting Bacteria classification G + C A +T

  5. 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

  6. 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.

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

  8. Fig 4.10

  9. Cytoplasmic membrane Protoplast Spheroplast L forms

  10. 4 groups based on cell wall composition • Gram positive cells • Gram negative cells • Bacteria without cell walls • Bacteria with chemically unique cell walls

  11. Gram positive Gram negative

  12. Gram positive Gram negative Fig 4.16

  13. Lipopolysaccharide O-antigen Highly variable n • Core • Heptoses • Ketodeoxyoctonic acid • Lipid A • Glucosamine disaccharide • Beta hydroxy fatty acids (Hydroxy myritic Acid)

  14. LPS functionEndotoxinsExotoxins

  15. Gram positive wall

  16. Gram negative cell wall

  17. Peptidoglycan

  18. Lipoteichoic acid Peptidoglycan-teichoic acid Cytoplasmic membrane Cytoplasm Lipopolysaccharide Porin Outer Membrane lipoprotein Periplasmic space Inner (cytoplasmic) membrane Cytoplasm

  19. r r r r r r r r r r Gram Positive Cell Envelope Lipoteichoic acid Peptidoglycan-teichoic acid Cytoplasmic membrane Cytoplasm

  20. Glycocalyx • Coating of molecules external to the cell wall, made of sugars and/or proteins • 2 types • capsule - highly organized, tightly attached • slime layer - loosely organized and attached • Functions • attachment • inhibits killing by white blood cells • Receptor (K antigen)

  21. 2 Types of Glycocalyx

  22. Biofilms

  23. Flagella

  24. Monotrichous lophotrichous amphitrichous peritrichous

  25. Fig 4.2b

  26. Fimbrae • Adhesion to other cells and surfaces

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

  28. Conjugation

  29. endospores

  30. Important components in endospore: CalciumDipicolinic Acid

  31. Sporulation

  32. The endospore

  33. Major Taxonomic Groups of Bacteria • 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

  34. Grwth in Bacteria • Temperature • Nutrients • pH • Osmotic pressure

  35. Temperature • Minimum temperature – lowest temperature that permits a microbe’s growth and metabolism • Maximum temperature – highest temperature that permits a microbe’s growth and metabolism • Optimum temperature – promotes the fastest rate of growth and metabolism

  36. 3 temperature adaptation groups

  37. Bacterial Metabolism • Phototroph • Photoautotroph (Photolitotroph) • Photoheterotroph (Photoorganotroph) • Chemotroph • Chemoautotroph (Chemolitotroph • Chemoheterotroph (Chemoorganotroph)

  38. Stages of metabolism in chemoheterotrophic bacteria • Digestion • Absorption(Passive and active transportation) • Preparation for oxidation • Oxidation

  39. Oxygen requirements

  40. Fermentation • Incomplete oxidation of glucose or other carbohydrates in the absence of oxygen • Uses organic compounds as terminal electron acceptors • Yields a small amount of ATP • Production of ethyl alcohol by yeasts acting on glucose • Formation of acid, gas & other products by the action of various bacteria on pyruvic acid

  41. Fermentation

  42. Binary division

  43. Growth Curve

  44. Continuous Culture, Chemostat Chemostats are a means of keeping a culture in log phase indefinitely.

  45. Methods in bacterial identification • Microscopic morphology • Macroscopic morphology – colony appearance • Physiological / biochemical characteristics • Chemical analysis • Serological analysis • Genetic & molecular analysis • G + C base composition • DNA analysis using genetic probes • Nucleic acid sequencing & rRNA analysis

  46. Bacterial Colonies • Standard Bacterial Count • Colony-Forming Units • Plaque-Forming Units • Spread Plate • Pour Plate • Soft-Agar Overlay

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