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Exploring Prokaryotes: Cellular Diversity and Function

Delve into the classification, structure, and functions of prokaryotes in various ecosystems. Learn about bacterial diversity, cell interiors, and genetic variation, as well as their vital roles as pathogens and beneficial organisms.

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Exploring Prokaryotes: Cellular Diversity and Function

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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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