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Prokaryotes

Domain Bacteria. Domain Archaea. Domain Eukarya. Common ancestor. Prokaryotes. Domain Bacteria Domain Archaebacteria. Domain Bacteria. Domain Archaea. Domain Eukarya. Common ancestor. What characteristics make Archaea more like eukaryotes than prokaryotes?.

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Prokaryotes

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

  2. Domain Bacteria Domain Archaea Domain Eukarya Common ancestor What characteristics make Archaea more like eukaryotes than prokaryotes? • No peptidoglycan in cell wall • More than 1 RNA polymerase • Some introns • Met is 1st amino acid in protein synthesis • Ribosomes more like eukarytoes (Streptomycin does not kill archaea)

  3. 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 Microbes alwaysfind a way tomake a living!

  4. Bacterial diversity rods and spheres and spirals

  5. eukaryote cell prokaryotecell Prokaryote Structure • Unicellular • bacilli, cocci, spirilli • Size • 1/10 size of eukaryote cell • 1 micron (1um) • Internal structure:

  6. Prokaryote vs. Eukaryote Chromosome Prokaryote Eukaryote double helix

  7. 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 • small supplemental circles of DNA • direct transfer of DNA conjugation

  8. Metabolic Relation to Oxygen • How are bacteria categorized by the effect that oxygen has on growth? • Obligate aerobes • Facultative anaerobes • Obligate anaerobes • What role do prokaryotes play in nitrogen cycling? • Only way that nitrogen gas can be incorporated into organic molecules

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

  10. Origins of Metabolic Diversity • Heterotrophs most likely came before photoautotrophs (parsimony) • Glycolysis was probably the first metabolic pathway • Natural selection favored autotrophs as heterotrophs depleted food supply • Cyanobacteria introduce chl a and oxygen gas.

  11. Cell Wall • What are the functions of the cell wall in prokaryotes? • Maintain cell shape • Protection • Prevent bursting in hypotonic environment • Made of peptidoglycan • Why is some food preserved by salting it? • Hypertonic environment plasmolyzes bacterial cells

  12. 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

  13. Prokaryotic metabolism • How do bacteria acquire their energy & nutrients? • photoautotrophs • photosynthetic bacteria • chemoautotrophs • oxidize inorganic compounds • nitrogen, sulfur, hydrogen… • heterotrophs • live on plant & animal matter • decomposers & pathogens

  14. Disease • Disease – • exotoxins release poisons such as botulism and cholera • Endotoxins seen in outer membrane of gram neg. bacteria (Salmonella) • What are Koch’s postulates and why are they important? • Koch’s postulates used to isolate pathogen causing disease

  15. Bacteria as pathogens • Disease-causing microbes • plant diseases • wilts, fruit rot, blights • animal diseases • tooth decay, ulcers • anthrax, botulism • plague, leprosy, “flesh-eating” disease • STDs: gonorrhea, chlamydia • typhoid, cholera • TB, pneumonia • lyme disease

  16. Bacteria as beneficial (& necessary) • Life on Earth is dependent on bacteria • recycling of nutrients from dead to living • 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

  17. Germinating akinetes

  18. Got any Questions?? Ask da’ Boss!

  19. Gram positive Gram negative Are these bacteria Gram + or Gram –?

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