Ch.28 eukaryotic diversity

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Ch.28 eukaryotic diversity

  1. 1. The Origins of Eukaryotic Diversity Chapter 28
  2. 2. Protists• 1st eukaryotes• Protists lived 2 billion years before the evolution of plants, fungi & animals• Most diverse group of eukaryotes• Live anywhere there is water• Protists could include as many as 20 kingdoms
  3. 3. Definition of Protists• Mostly single-cellular• Some colonial and multicellular• Eukaryotic
  4. 4. Protist Nutrition• Aerobic, use mitochrondria• Can be – Photoautotrophs (algae) – Heterotrophs (protozoa) – Mixotrophs
  5. 5. Protist Motility• Cilia or flagella – Most have one at some point in life – 9+2 arrangement of microtubules
  6. 6. Trends toward the evolution of eukaryotes• Multicellular prokaryotes• Prokaryotic communities• Compartmentalization of functions within cell
  7. 7. Serial Endosymbiosis
  8. 8. Secondary Endosymbiosis
  9. 9. A hypothetical history of plastids in the photosynthetic eukaryotes
  10. 10. Traditional hypothesis for how the three domains of life are related
  11. 11. An alternative hypothesis for how the three domains of life are related
  12. 12. The kingdom Protista problem
  13. 13. A tentative phylogeny of eukaryotes
  14. 14. Evolution of Multicellularity• Eukaryotes – Organization allowed for development of more complex structures – Opportunities to specialize & adapt• Multicellularity evolved several times – Multicellular algae (seaweeds) – Ancestors of plants, fungi & animals
  15. 15. Survey of Protistan Diversity
  16. 16. Diplomonadida & Parabasala• Lack mitochondria Giardia lamblia Trichomonas vaginalis
  17. 17. Euglenazoa• Photosynthetic & heterotrophic flagellates
  18. 18. Alveolata: unicellular protists w/ subcellular cavities• Dinoflagellates
  19. 19. Alveolata: unicellular protists w/ subcellular cavities• Apicomplexans
  20. 20. Alveolata: unicellular protists w/ subcellular cavities• Ciliates
  21. 21. Ciliates: Stentor (left), Paramecium (right)
  22. 22. Conjugation and genetic recombination in Paramecium caudatum
  23. 23. Stramenopila: Water molds & Heterokont algae “hairy” flagella• Oomycota (water molds) – Resemble fungi (but not closely related) – Cell walls made of cellulose – Diploid life cycle
  24. 24. The life cycle of a water mold
  25. 25. Stramenopila: Water molds & Heterokont algae “hairy” flagella• Heterokont algae – 3-membraned plastids – Types • Diatoms • Golden algae • Brown algae
  26. 26. Stramenopila: Water molds & Heterokont algae “hairy” flagella• Diatoms – Box-like silica walls – Freshwater & marine plankton
  27. 27. Stramenopila: Water molds & Heterokont algae “hairy” flagella• Golden algae• (Chrysophyta) – Yellow and brown pigments • (carotene and xanthophyll) – Can form resistant cysts
  28. 28. Stramenopila: Water molds & Heterokont algae “hairy” flagella• Brown algae (Phaeophyta) – Largest & most complex algae – Brown pigments
  29. 29. Alternation of Generations
  30. 30. Rhodophyta: Red Algae• Lack flagella• Phycoerythrin – red pigment (a phycobilin)• Can absorb light in deep water• Most are marine
  31. 31. Chlorophyta: Green Algae• Share common ancestor with plants• Most are freshwater• Unicellular, colonial & multicellular species• Some are seaweeds• Form lichens
  32. 32. Protists that Use Pseudopodia• Rhizopods (amoebas) – Move and feed w/ psuedopodia• Actinopods – Axopodia help cell float and feed by phagocytosis• Foraminferans – Porous, calcareous shells – Cytoplasmic strands extend through pores and function in swimming, shell formation & feeding
  33. 33. Use of pseudopodia for feeding: Amoeba
  34. 34. Actinopods: Heliozoan (left), radiolarian (right)
  35. 35. Foraminiferan
  36. 36. Mycetozoa: Slime Molds• Resemble fungi b/c of convergent evolution (not actually related)• Plasmodial slime molds – Heterotrophic – Grow on rotting plant material – Feeding stage is called a plasmodium • Multinucleate amoeboid mass• Cellular slime molds – Feeding stage: haploid amoeboid cells – In absence of food: form a slug-like mass
  37. 37. Plasmodial slime mold
  38. 38. Figure 28.29 The life cycle of a plasmodial slime mold, such as Physarum
  39. 39. The life cycle of a cellular slime mold (Dictyostelium)

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