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Chapter 19 Bacteria & Viruses

Chapter 19 Bacteria & Viruses. 19.1 Prokaryotes. Single-celled Lack nucleus Smallest, most common microorganism. Classification. E. Coli bacteria. Eubacteria (D/Bacteria) Larger kingdom; greater diversity Cell wall w/peptidoglycan (carbo). Shapes. Archaebacteria (D/Archaea)

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Chapter 19 Bacteria & Viruses

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  1. Chapter 19 Bacteria & Viruses 19.1 Prokaryotes

  2. Single-celled • Lack nucleus • Smallest, most common microorganism

  3. Classification

  4. E. Coli bacteria • Eubacteria (D/Bacteria) • Larger kingdom; greater diversity • Cell wall w/peptidoglycan (carbo) • Shapes

  5. Archaebacteria (D/Archaea) • Extremist (anaerobic methanogens) • Cell wall w/out peptidoglycan • DNA sequence of key genes = eukaryotes Bacteria in hot springs Billion yr old cyanobacteria

  6. Identification • Shapes • Bacilli: rod-shaped • Cocci: spherical • Streptococcus: chains • Staphylococcus: clusters • Spirilla: spiral-shaped Streptococcus Staphylococcus

  7. Cell Walls • Gram + : single layer; stain purple • Gram - : double layer; stain pink (disease)

  8. Movement • Flagella: whip-like structure

  9. Energy • Autotrophs (make food) • Photoautotrophs: cyanobacteria (aerobic) • Chemoautotrophs: anaerobic • Heterotrophs (obtain food) Cyanobacteria

  10. Respiration • Obligate aerobes: respire/need O2 • Obligate anaerobes: ferment/killed w/ O2 • (C. botulinum) • Facultative anaerobes: resp/ferm Flesh eating bacteria Tetanus C. botulinum produces the potent nerve toxin that causes botulism.

  11. Reproduction • 20 min doubling time • Binary Fission: Asexual reproduction • DNA replicated & divides • Identical daughter cells

  12. Conjugation: Sexual reproduction • Genetic material exchange • Protein bridge forms between bacteria (pilli)

  13. Endospore • Internal wall enclosing DNA/cytoplasm • Remains dormant (months to centuries)

  14. 19.2 Bacteria in Nature • Decomposers • Recycle nutrients • Sewage treatment

  15. Nitrogen Fixation • Fixing N2 (air) to NH3 (ammonia=fertilizr) • Plants need N for AA to make proteins

  16. Disease • Pathogens • Tissue damage: tuberculosis (lungs) Table 19.6 Tissue specificity as a factor in infectious disease

  17. Botulism: no contraction (death by respiratory failure) Tetanus: permanent contraction (death by respiratory failure) • Toxins: salmonella, tetanus, botulism

  18. Vaccines: stimulate immune system • Antibiotics: block growth/reproduction

  19. Human Uses • Food; Industrial; Genetic engineering BLOCKING OUT GAS. Unlike the left tower, which uses chemicals, the tower on the right at this wastewater-treatment plant now uses bacteria-covered foam blocks (inset) to eliminate the hydrogen sulfide bubbling from treated sewage. Bacteria products for biological filters BLOCKING OUT GAS.This wastewater-treatment tower bacteria-covered foam blocks (inset) to eliminate the hydrogen sulfide bubbling from treated sewage.

  20. Controlling • Sterilization: Heat; Disinfectant • Food: Refrigerate, heat, seal, preserve

  21. 19.3 Viruses

  22. What is it? • Non-living; lack cells; need host to reproduce • Smaller/simpler than smallest cells • DNA/RNA core; protein coat (capsid)

  23. Infection • Species specific (bacteriophage = only bacteria)

  24. Lytic: host cell destroyed • Virus enters host (DNA/RNA injected) • Replicates using materials of host DNA • Host burst and releases many new virus Lytic Viral Reproduction Phase

  25. Lysogenic: uses host indefinitely • Virus embeds DNA (prophage) into host DNA • Replicated w/ host DNA • Will eventually becomes lytic Lysogenic Phase

  26. Disease • Vaccines: must receive before infection • Cancer: oncogenic virus • Disrupt cell growth/division

  27. Retrovirus: contain RNA • DNA copy made and inserts into host DNA • RNA to DNA (backwards) • AIDS

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