BIOL 108 Chp 13 Evolution and Diversity Among the Microbes - Part 1


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BIOL 108 Chp 13 Evolution and Diversity Among the Microbes - Part 1

  1. 1. Chapter 13 Evolution & Diversity Among the Microbes BIOL 108 Intro to Bio Sci Rob Swatski Assoc Prof Biology HACC- HACC-York
  2. 2. Learning Goals Describe Discuss Discuss Know that how, in how how Know bacteria humans, Archaea viruses there are may be bacteria exploit are at the microbes the most can have some of borderin all three diverse of harmful or the most between domains all beneficial extreme living and organisms health habitats non-living effects 2
  3. 3. 13.1–13.2 There aremicrobes in all three domains.
  4. 4. 13.1 Microbes are the simplest,but most successful organisms on earth. 4
  5. 5. How can a microbe function when its body is just a single cell? Amoeba as an example 5
  6. 6. 6
  7. 7. How would you decide whether a group of organisms can be considered successful? 7
  8. 8. Microbes Are Genetically Diverse >500,000 kinds Millions more expected to be distinguished! 8
  9. 9. Microbes Can Live Almost Anywhere and Eat Almost Anything 9
  10. 10. Microbes areabundant! 10
  11. 11. Take- Take-Home Message 13.1 Microbes are simple, They can livebut they do everything anywhere, from that multicellular moderate to extreme organisms do. environments. There are millions of different kinds of microbes on earth, in enormous numbers. 11
  12. 12. 13.2 Microbes are not all evolutionarily related. 12
  13. 13. 13
  14. 14. Take-Take-Home Message 13.2 Microbes are organisms too small to see without magnification and are grouped together only because they are small, not because of evolutionary relatedness. They occur in all three domains of life, and include viruses that are not in any of the domains. 14
  15. 15. 13.3−13.5 Bacteriamay be the mostdiverse of allorganisms.
  16. 16. 13.3 What are bacteria? 16
  17. 17. 17
  18. 18. 18
  19. 19. Take-Take-Home Message 13.3 Bacteria are efficient single- celled organisms, with an envelope surrounding the cytoplasm, which contains the DNA (they have no nuclei and no intracellular organelles). Bacterial cells undergo binary fission, and a single cell can grow into a colony of cells. 19
  20. 20. 13.4 Bacterial growth and reproduction is fast and efficient. 20
  21. 21. Bacteria Carry Genetic Information in Two Structures1) A circular DNA molecule called the chromosome (1 or more)2) Circular DNA molecules called plasmids • metabolic plasmids • resistance plasmids • virulence plasmids 21
  22. 22. Would it be useful to be able totransfer genetic information from one adult human to another? 22
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  27. 27. Bacterial Reproduction If bacteria can reproduce from one cell tothousands in a few hours, why don’t they totally overrun life on earth? 27
  28. 28. Bacterial Reproduction A given bacterium has a generation time of one hour. This means that the number of bacteria present will double in one hour. Assume you start out with onebacterial cell that reproduces by binary fission, which of course means that no other cell is needed for reproduction to take place. How many cells will there be after 24 hours? 28
  29. 29. Take- Take-Home Message 13.4 They have efficiently organized chromosomes—genes are Bacteria grow rapidly. organized in groups with related functions and virtually all the DNA codes for proteins. Bacteria sometimes carry thegenes for specialized traits on DNA can also be transferred small DNA molecules called laterally between bacterial plasmids that can be cells by transduction ortransferred from one bacterial transformation.cell to another by conjugation. 29
  30. 30. 13.5 Metabolic diversity among the bacteria is extreme. 30
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  34. 34. Take-Take-Home Message 13.5 Some bacteria eat organic molecules, some eat minerals, and still other bacteria carry out photosynthesis. About 2.6 billion years ago, the photosynthesizing bacteria were responsible for the first appearance of free oxygen in the Earths atmosphere. 34
  35. 35. 13.6–13.9 In humans, bacteria can have harmful or beneficialhealth effects.
  36. 36. 13.6 Manybacteria arebeneficial. 36
  37. 37. You Owe Your Life to Bacteria Your normal flora • benign bacteria that are your first line of defense against infection by harmful bacteria Probiotic therapy • a method of treating infections by deliberately introducing benign bacteria 37
  38. 38. Take- Take-Home Message 13.6 A disease-causing bacterium must colonize your bodyYour body fights bacteria before it can make you sick, with bacteria. and your body is already covered with harmless bacteria. If the population of harmless bacteria is dense enough, it will stop invading bacteria. 38
  39. 39. 13.7 Bacteria cause many human diseases. Pathogenic Bacteria 39
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  41. 41. 41
  42. 42. Take-Take-Home Message 13.7 Some bacteria always cause disease and others do no harm except under certain conditions. For example, Streptococcus pyogenes can be harmless, but under some conditions it releases toxins that are responsible for strep throat, scarlet fever, and necrotizing fasciitis (caused by the flesh-eating strains). 42
  43. 43. 13.8 Bacteria’s resistance to drugs can evolve quickly. quickly. 43
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  46. 46. Where do antibiotics come from, and why do they soquickly lose their effectiveness? Chemicals that kill! 46
  47. 47. Bacteria and other microbes resist antibiotics in a variety of ways: Pumping antibiotics out of their cell Proteins that bind to the antibiotic molecule and block its lethal effect Enzymes that break down the antibiotic molecules that are then used as fuel to help the bacteria grow faster 47
  48. 48. Why is it essential to take everydose of an antibiotic prescribed by a doctor? 48
  49. 49. 49
  50. 50. Take- Take-Home Message 13.8 The genes that allow bacteria to combat antibiotics are located onMicrobes routinely evolve plasmids, and plasmid transferresistance to antibiotics. allows an antibiotic-resistant bacterium to pass that resistance to other bacteria. Excessive use of antibiotics in medicine and agriculture has made several pathogenic bacteria resistant to every antibiotic, and infections caused by these bacteria are nearly impossible to treat. 50
  51. 51. 13.10–13.12 Archaeaexploit some of the most extreme habitats.
  52. 52. 13.10 Archaea are profoundly different from bacteria. 52
  53. 53. Additional Differences among Bacteria, Archaea, and Eukarya Archaea, Chemical compositions of the plasma membranes, cell walls, and the flagellae Eukaryahave a distinct cell nucleus and a nuclear membrane; Bacteria and Archaea do not . 53
  54. 54. Take- Take-Home Message 13.10 Archaea and bacteria may look similar, but they have large and Archaea show a set of significant differences in their characteristics that places them DNA sequences, as well asbetween bacteria and eukaryotes differences in their plasma on the tree of life. membranes, cell walls, and flagella. Furthermore, neither archaea nor bacteria resemble eukarya in one key way: only eukarya have a distinct cell nucleus and nuclear membrane. 54
  55. 55. 13.11 Archaea thrive in habitats too extreme for most other organisms. 55
  56. 56. Extremophiles 56
  57. 57. 57
  58. 58. Take- Take-Home Message 13.11Archaeans can tolerate extremephysical and chemical conditions that are impossible for most other living organisms, but they also live in moderate conditionsand even in the human intestine. 58
  59. 59. 13.12 Much Archaean diversity has yet to be discovered. 59
  60. 60. Important applications in bioengineering andenvironmental remediation 60
  61. 61. Enormous Potential for Industries: Bioremediation Degrade hydrocarbon Clearing mineral deposits from pipes in the cooling systems of power plants 61
  62. 62. Take-Take-Home Message 13.12 Archaea are hard to study because many require extreme heat or pressure to grow, and these conditions are not easy to provide in a laboratory. But the ability of archaea to grow in such extreme conditions makes them potentially valuable for industrial and environmental purposes. 62
  63. 63. 13.16–13.19Viruses are at the border between living and non-living.
  64. 64. 13.16 Viruses are not exactly living organisms. 64
  65. 65. 65
  66. 66. Take- Take-Home Message 13.16 A virus takes over the A virus is not alive, but it protein-making machinerycan carry out some of the of the host cell to produce same functions as living more viral genetic materialorganisms, provided that it (RNA or DNA) and more can get inside a cell. viral protein. The viral proteins and genetic material are assembled into new virus particles and released from the cell. 66
  67. 67. 13.17 Viruses are responsible for many health problems. 67
  68. 68. Why do flu viruses change quickly? DNA vs. RNA viruses 68
  69. 69. Take- Take-Home Message 13.17 DNA viruses are relatively stable because DNAMany diseases are caused replication enzymes check by viruses. for errors and correct them during replication. RNA viruses change quickly because RNA replication enzymes do not have error- checking mechanisms. 71
  70. 70. 13.18 Viruses infect a wide range of organisms. 72
  71. 71. 73
  72. 72. What role does a pig play in thetransmission of virus from a bird to a human? 74
  73. 73. 75
  74. 74. Bird Flu Sofar requires close contact with infected flocks of birds or by eating birds that had died of the virus. WHO and national health agencies are preparing for a worldwide pandemic. 76
  75. 75. Mixing RNA Pig +bird flu virus + human virus = might produce a new form of the virus that carries the genes that make the bird flu lethal to humans AND the gene that codes for the host- entry glycoprotein. 77
  76. 76. Take-Take-Home Message 13.18 Glycoproteins on the surfaces of viruses determine what cells they can invade. Most viruses infect just one species, or only a few closely related species, and enter only one kind of cell in that species. 78