CHAPTER 27 Protists and the Dawn of the Eukarya

1. CHAPTER 27Protists and the Dawn of the Eukarya

2. Chapter 27: Protists and the Dawn of the Eukarya Protists Defined The Origin of the Eukaryotic Cell General Biology of the Protists Protist Diversity

3. Chapter 27: Protists and the Dawn of the Eukarya Euglenozoa Alveolata Stramenopila Rhodophyta

4. Chapter 27: Protists and the Dawn of the Eukarya Chlorophyta Choanoflagellida A History of Endosymbiosis Some Recurrent Body Forms

5. Protists Defined • In this book we define the protists as all eukaryotes that are not plants, fungi, or animals. • They are not a monophyletic group. 5

6. The Origin of the Eukaryotic Cell • The modern eukaryotic cell arose from an ancestral prokaryote. • Probable steps included loss of the cell wall and inward folding of the plasma membrane. Review Figure 27.2 6

7. figure 27-02.jpg Figure 27.2 Figure 27.2

8. The Origin of the Eukaryotic Cell • An infolded plasma membrane attached to the chromosome may have led to formation of a nuclear envelope. • A primitive cytoskeleton evolved. Review Figure 27.3 8

9. figure 27-03a.jpg Figure 27.3 – Part 1 Figure 27.3 – Part 1

10. figure 27-03b.jpg Figure 27.3 – Part 2 Figure 27.3 – Part 2

11. The Origin of the Eukaryotic Cell • The first truly eukaryotic cell was larger than its prokaryote ancestor, and possibly possessed one or more eukaryotic type flagella. 11

12. The Origin of the Eukaryotic Cell • Prokaryotic cells incorporated as endosymbionts gave rise to eukaryotic organelles. • Peroxisomes may have been the first organelles of endosymbiotic origin. • Mitochondria evolved from proteobacteria, • Chloroplasts from cyanobacteria. • Cells with nuclei probably appeared before those with mitochondria. Review Figure 27.3 12

13. General Biology of the Protists • Most protists are aquatic; some live within other organisms. • The great majority are unicellular and microscopic but, many are multicellular and a few are enormous. 13

14. General Biology of the Protists • “Protozoan” is an outdated term applied to protists once classified as animals. • “Alga” is an outdated term applied to photosynthetic protists. 14

15. General Biology of the Protists • Protists vary in modes of nutrition, metabolism, and locomotion. • Some protist cells contain contractile vacuoles, some digest food in food vacuoles. Review Figures 27.5, 27.6 15

16. figure 27-05.jpg Figure 27.5 Figure 27.5

17. figure 27-06.jpg Figure 27.6 Figure 27.6

18. General Biology of the Protists • Protists have a variety of cell surfaces, some of them protective. 18

19. General Biology of the Protists • Many protists contain endosymbiotic prokaryotes. • Some are endosymbiotic in other cells, including other protists. • Some endosymbiotic protists perform photosynthesis. 19

20. General Biology of the Protists • Most protists reproduce both asexually and sexually. 20

21. Protist Diversity • Molecular and other techniques are enabling biologists to identify many monophyletic groups of protists. Review Figure 27.9, Table 27.1 21

22. figure 27-09.jpg Figure 27.9 Figure 27.9

23. table 27-01.jpg Table 27.1 Table 27.1

24. Euglenozoa • The Euglenozoa are a monophyletic group of unicellular protists with flagella. 24

25. Euglenozoa • Euglenoids are Euglenozoa that are often photosynthetic and have anterior flagella. See figure 10

26. Euglenozoa • Kinetoplastids are Euglenozoa that have a single, large mitochondrion, in which RNA is edited. 26

27. Alveolata • The Alveolata are a monophyletic group of unicellular organisms with alveoli beneath their plasma membranes. 27

28. Alveolata • Dinoflagellates are marine alveolates with a unique color. • They are major contributors to world photosynthesis. • Many are endosymbionts; they contribute to coral reef growth. • Dinoflagellates cause“red tides.” 28

29. Alveolata • Apicomplexans are parasitic alveolates. • Their spores, containing a mass of organelles, are adapted to the invasion of host tissue. • The apicomplexan Plasmodium causes malaria. Review Figure 27.13 29

30. figure 27-13.jpg Figure 27.13 Figure 27.13

31. Alveolata • Ciliates are alveolates that move via cilia and have two kinds of nuclei. • The macronuclei control the cell with transcription and translation,and are responsible for genetic recombination by conjugation. • Some ciliates have a complex internal structure. Review Figures 27.15, 27.16, 27.17 31

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33. figure 27-16.jpg Figure 27.16 Figure 27.16

34. figure 27-17a.jpg Figure 27.17 – Part 1 Figure 27.17 – Part 1

35. figure 27-17b.jpg Figure 27.17 – Part 2 Figure 27.17 – Part 2

36. Stramenopila • Stramenopiles typically have two flagella of unequal length, the longer bearing rows of tubular hairs. • Some groups are photosynthetic. 36

37. Stramenopila • Diatoms are unicellular stramenopiles, many of which have complex, two-part, glassy cell walls. • They contribute to world photosynthesis. Review Figure 27.19 37

38. figure 27-19.jpg Figure 27.19 Figure 27.19

39. Stramenopila • The brown algae are predominantly multicellular, photosynthetic stramenopiles. • They include the largest of all protists. • Some show considerable tissue differentiation. 39

40. Stramenopila • In many multicellular photosynthetic protists and all plants, haploid and diploid cells undergo mitosis and alternation of generations. • The diploid sporophyte generation forms spores by meiosis which become haploid. • The haploid gametophyte generation forms gametes by mitosis and yields zygotes: the next generation of sporophytes. Review Figure 27.22 40

41. figure 27-22.jpg Figure 27.22 Figure 27.22

42. Stramenopila • Oomycetes are a group of nonphotosynthetic stramenopiles . • The oomycetes are coenocytic. • They are diploid for most of their life cycle. 42

43. Rhodophyta • Red algae (Rhodophyta) are multicellular, photosynthetic protists that have a characteristic storage product (floridean starch) and lack flagellated reproductive cells. 43

44. Chlorophyta • The Chlorophyta are often multicellular, contain chlorophylls a and b, and use starch as a storage product. • Their life cycles include the isomorphic alternation of generations of Ulva and the haplontic life cycle of Ulothrix. Review Figures 27.26, 27.27 44

45. figure 27-26.jpg Figure 27.26 Figure 27.26

46. figure 27-27.jpg Figure 27.27 Figure 27.27

47. Chlorophyta • The chlorophytes are sister to a lineage including other green algae and the plant kingdom. 47

48. Choanoflagellida • The Choanoflagellida are protists with flagella and a body type similar to a characteristic type of sponge cell. • The Choanoflagellida are sister to the animal kingdom. 48

49. A History of Endosymbiosis • Primary endosymbiosis of a cyanobacterium and a eukaryote gave rise to the chloroplasts of green algae, plants, and red algae. Review Figure 27.29 49

50. figure 27-29.jpg Figure 27.29 Figure 27.29