Biology - Chp 20 - Protists - PowerPoint


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Biology - Chp 20 - Protists - PowerPoint

  1. 1. Protists Chapter 20 Protists
  2. 2. What is a Protist? <ul><li>The kingdom Protista is a diverse group that may include more than 200,000 species </li></ul><ul><li>Biologists have argued for years over the best way to classify protists, and the issue may never be settled </li></ul><ul><li>In fact, protists are defined less by what they are and more by what they are not </li></ul>
  3. 3. Protist <ul><li>Eukaryotes that are not members of the kingdoms Plantae, Animal, or Fungi </li></ul><ul><li>Most protists are unicellular, but some are multicellular </li></ul>
  4. 4. Endosymbiotic theory <ul><li>Theory that eukaryotic cells formed from a symbiosis among several different prokaryotic organisms </li></ul>
  5. 5. Evolution of Protists <ul><li>The kingdom “Protista” means “the very first” which is appropriate because they were the first eukaryotic organism on Earth </li></ul><ul><li>It is hypothesized that the first Protists evolved from a symbiosis of several prokaryotic cells </li></ul>
  6. 6. Endosymbiotic theory
  7. 7. Endosymbiotic theory
  8. 8. Endosymbiotic theory
  9. 9. Classification of Protists <ul><li>Protists are so diverse that biologists suggest that they should be broken up into several kingdoms </li></ul><ul><li>Currently biologists don’t agree how this should be done </li></ul><ul><li>Therefore we will look at Protists as if they belong in the same kingdom and classify them by how they obtain nutrition </li></ul>
  10. 10. Heterotrophs <ul><li>Can’t make their own food </li></ul><ul><li>Many are capable of locomotion (moving) </li></ul>
  11. 11. Animal-like Protists
  12. 12. Flagellates
  13. 13. Cilliates
  14. 14. Sarcodines
  15. 15. Sporozoans
  16. 16. Malaria
  17. 17. Plant-like Protists <ul><li>Many protists contain the green pigment chlorophyll and carry out photosynthesis </li></ul><ul><li>Autotrophic </li></ul><ul><li>However, they are not classified as plants, they are algae </li></ul>
  18. 18. Euglena
  19. 19. Volvox
  20. 20. Diatoms
  21. 21. Dinoflagellates
  22. 22. Ecology of Unicellular Algae <ul><li>Plant-like protists play a major ecological role on earth </li></ul><ul><li>They make up a large part of the phytoplankton </li></ul>
  23. 23. Phytoplankton <ul><li>The population of small photosynthetic organisms near the surface of the ocean </li></ul><ul><li>About 1/2 of photosynthesis on earth occurs in phytoplankton </li></ul>
  24. 24. Phytoplankton
  25. 25. Green algae
  26. 26. Red Algae
  27. 27. Algal Blooms <ul><li>Sometimes populations of algae grows in enormous masses called blooms </li></ul><ul><li>These algal blooms deplete the water of nutrients and can release toxins into the water </li></ul><ul><li>Ex.) Red tide </li></ul>
  28. 28. Red tide
  29. 31. Fungus-like Protist <ul><li>Like fungi, the fungus-like protist are heterotrophs that absorb nutrients from dead or decaying organic matter </li></ul><ul><li>But unlike true fungi, fungus-like protists have centrioles </li></ul><ul><li>They also lack the chitin cell walls of true fungi </li></ul>
  30. 32. Slime molds <ul><li>Slime molds are fungus-like protists that play a key role in recycling organic material </li></ul><ul><li>Found in places that are damp and rich in organic matter </li></ul>
  31. 34. Water Molds <ul><li>Fungus-like protists that thrive on dead decaying organic matter in water and some are plant parasites on land </li></ul>
  32. 35. Ecology of Fungus-like Protists <ul><li>They are important as recyclers or organic material </li></ul><ul><li>They can cause diseases however </li></ul><ul><ul><li>Mildews and blights </li></ul></ul><ul><ul><li>Potato famine 1845 and 1851 </li></ul></ul>