1 / 53

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.

africa
Download Presentation

Fig. 4.1

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  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

More Related