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Chapter 27

Chapter 27. Prokaryotes and the Origins of Metabolic Diversity. Eukaryote. Prokaryote. Archaebacteria & Bacteria. Classification. Old 5 Kingdom system Monera , Protists, Plants, Fungi, Animals New 3 Domain system reflects a greater understanding of evolution & molecular evidence

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Chapter 27

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  1. Chapter 27 • Prokaryotes and the Origins of Metabolic Diversity

  2. Eukaryote Prokaryote Archaebacteria&Bacteria Classification • Old 5 Kingdom system • Monera, Protists, Plants, Fungi, Animals • New 3 Domain system • reflects a greater understanding of evolution & molecular evidence • Prokaryote: Bacteria • Prokaryote: Archaebacteria • Eukaryotes • Protists • Plants • Fungi • Animals

  3. Domain Bacteria Domain Archaea Domain Eukarya Common ancestor Prokaryotes Domain Bacteria Domain Archaebacteria

  4. Bacteria live EVERYWHERE! • Bacteria live in all ecosystems • on plants & animals • in plants & animals • in the soil • in depths of the oceans • in extreme cold • in extreme hot • in extreme salt • on the living • on the dead

  5. Bacterial diversity Rods(bacilli) and spheres(cocci) and spirals(helical)…Oh My!

  6. eukaryote cell prokaryotecell Prokaryote Structure • Unicellular • bacilli, cocci, spirilli • Size • 1/10 size of eukaryote cell • 1 micron (1um) • Internal structure • no internal compartments • no membrane-bound organelles • only ribosomes • circular chromosome, naked DNA • not wrapped around proteins

  7. mitochondria chloroplast Variations in Cell Interior cyanobacterium(photosythetic) bacterium aerobic bacterium internal membranesfor respirationlike a mitochondrion(cristae) internal membranesfor photosynthesislike a chloroplast(thylakoids)

  8. outer membrane of lipopolysaccharides Gram-negative bacteria Gram-positive bacteria peptide side chains outer membrane cell wall peptidoglycan cell wall peptidoglycan plasma membrane plasma membrane protein Prokaryote Cell Wall Structure That’simportant foryour doctorto know! peptidoglycan = polysaccharides + amino acid chains lipopolysaccharides = lipids + polysaccharides

  9. Motility • 1- Flagella • 2- Helical shape (spirochetes) • 3- Slime • 4-Taxis (movement away or toward a stimulus)

  10. Form & Function • Nucleoid region (genophore: non-eukaryotic chromosome) • Plasmids • Asexual reproduction: binary fission (not mitosis) • “Sexual” reproduction (not meiosis): transformation~ uptake of genes from surrounding environment conjugation~ direct gene transfer from 1 prokaryote to another transduction~ gene transfer by viruses • Endospore: resistant cells for harsh conditions (250 million years!)

  11. Genetic variation in bacteria • Mutations • bacteria can reproduce every 20 minutes • binary fission • error rate in copying DNA • 1 in every 200 bacteria has a mutation • you have billions of E. coli in your gut! • lots of mutation potential! • Genetic recombination • bacteria swap genes • plasmids • small supplemental circles of DNA • conjugation • direct transfer of DNA conjugation

  12. Nutrition & Metabolism • Photoautotrophs: photosynthetic; harness light to drive the synthesis of organics (cyanobacteria) • Chemoautotrophs: oxidation of inorganics for energy; get carbon from CO2 • Photoheterotrophs: use light to generate ATP but get carbon in an organic form • Chemoheterotrophs: consume organic molecules for both energy and carbon saprobes-dead organic matter decomposersparasites-absorb nutrients from living hosts • Oxygen relationships: obligate aerobes; facultative anaerobes; obligate anaerobes

  13. Bacteria as pathogens • animal diseases • tooth decay, ulcers • anthrax, botulism • plague, leprosy, “flesh-eating” disease • STDs: gonorrhea, chlamydia • typhoid, cholera • TB, pneumonia • lyme disease opportunistic: normal residents of host; cause illness when defenses are weakened •Koch’s postulates: criteria for bacterial disease confirmation •exotoxins: bacterial proteins that can produce disease w/o the prokaryote present (botulism) •endotoxins: components of gram - membranes (Salmonella)

  14. Bacteria as beneficial (& necessary) • Life on Earth is dependent on bacteria • decomposers • recycling of nutrients from dead to living • nitrogen fixation • only organisms that can fix N from atmosphere • needed for synthesis of proteins & nucleic acids • plant root nodules • help in digestion (E. coli) • digest cellulose for herbivores • cellulase enzyme • produce vitamins K & B12 for humans • produce foods & medicines • from yogurt to insulin

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