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Chapter 21

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  1. Chapter 21 Prokaryotes & Viruses

  2. Taxonomy • Domain Eukarya • Kingdom Animalia • Phylum Chordata • Class Mammalia • Order Cetacea • Family Delphinidae • Genus Tursiops • Species truncatus • Bottlenose dolphin

  3. Domains • Eubacteria (Bacteria) • Archaebacteria (Archaea) • Eukarya • Kingdom Protista • Kingdom Fungi • Kingdom Plantae • Kingdom Animalia

  4. Prokaryotes vs. Eukaryotes • Prokaryotes—simplest, most “primitive” • bacteria • Eukaryotes— “true” cells, more “advanced” • Complex organisms, multicelled

  5. Prokaryotes • No membrane around nucleus • No true organelles • Single chromosome (nucleoid) • May have plasmids • Cell wall (most) • Reproduce by prokaryotic fission

  6. Bacterial Shapes • Coccus (cocci)—spherical • Bacillus (bacilli)—rod • Sprillum (spirilla)—spiral, twist

  7. Bacterial Structures • Cell wall • Peptidoglycan (polysaccharide) • Maintain shape • ID species • Gram-positive—thick wall • Stain purple • Gram-negative—thin wall • Stain pink

  8. Bacterial Structures • Glycocalyx—capsule or slime layer • Attach to structures (teeth, intestine, rocks, etc.) • Protection • Pili—thin, hair-like proteins • Adhere to surfaces • Adhere to other baceria • Flagellum • Movement

  9. Metabolism • Photoautotroph • Energy from sun (photosynthesis) • Carbon from CO2 • Chemoautotroph • Energy from simple compounds (iron, sulfur, etc.) • Carbon from CO2 • Photoheterotroph • Energy from sun • Carbon from organic compounds • Chemoheterotroph (most common kind) • Energy from simple compounds • Carbon from organic compounds

  10. Prokaryotic Fission • Similar to mitosis, but simpler • DNA duplicates • DNA molecules move to opposite sides of cell • New cell membrane & wall form across middle • Cell divides

  11. Conjugation • Transfer section of DNA from one cell to another • Transfers genes, characteristics • Antibiotic resistance

  12. Domain Eubacteria • Cyanobacteria • One of most primitive kind • Photoautotrophs • Produce oxygen • “Fix” nitrogen (convert N2 gas to nitrogen compounds)

  13. Domain Eubacteria • Proteobacteria • All gram-negative • Chemoautotrophs • Important to nutrient cycles • Rhizobium • Roots of legumes (peas, soybeans, etc.)

  14. Domain Eubacteria • Chlamydia • Intracellular parasites • One species causes STD • Spirochaetes • Free-living, parasites, or symbionts • Motile “springs” • Borreliaburgdorferi—Lyme disease

  15. Domain Eubacteria • Gram-positives • Still being sorted out • Chemoheterotrophs (most) • Lactobacillus—dairy foods (i.e. yogurt) • Bacillus anthracis—anthrax • Clostridium tetani—tetanus

  16. Domain Archaebacteria • “Extremophiles” • Primitive, but resemble other bacteria • Different cells walls (no peptidoglycan)

  17. Domain Archaebacteria • Thermophiles • Heat lovers • Sulfur used to make ATP • Temperatures can exceed 110o C

  18. Domain Archaebacteria • Methanogens • Create methane gas • Marshes, Antarctica, deep ocean • Symbionts (termites, cattle) • Important to carbon cycling • Anaerobes

  19. Domain Archaebacteria • Halophiles • Salt lovers • Environments 10x salinity of sea water • Dead Sea, Great Salt Lake

  20. Living things must…. • Acquire energy • Metabolize • Maintain homeostasis • Grow • Reproduce • Respond • Adapt

  21. Viruses • Noncellular • Infectious parasite • Two main characteristics • Protein coat around nucleic acid (DNA or RNA) • Cannot reproduce itself

  22. Viruses • Herpes • Smallpox • Hepatitis B • Rhino virus (common cold) • HIV • Influenza • Rabies

  23. Viral Multiplication • Attachment • Penetration • Replication & synthesis • Assembly • Release

  24. Viral Multiplication • Lytic Pathway—host cell bursts (lysis) & dies, releasing viruses • Very rapid

  25. Viral Multiplication • Lysogenic Pathway—host cell lives, viral DNA merges w/ host’s & is duplicated w/ host DNA

  26. Viral Multiplication • Latent Period • virus in lysogenic pathway, reproducing but not showing disease • Stress or other stimulus signals virus into lytic pathway • Herpes virus