1. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Chapter 28 Protists

2. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings WORD ROOTS -PHYTE: CON-: -MORPH: ISO-: PSUEDO-: -PODIUM: THALLOS-:

3. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Overview: A World in a Drop of Water Even a low-power microscope can reveal a great variety of organisms in a drop of pond water These amazing organisms belong to the diverse kingdoms of mostly single-celled eukaryotes informally known as protists Advances in eukaryotic systematics have caused the classification of protists to change significantly

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5. Concept 28.1: Protists are an extremely diverse assortment of eukaryotes Protists are more diverse than all other eukaryotes and are no longer classified in a single kingdom. Most protists are unicellular, but there are some colonial and multicellular species.

6. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Protists, the most nutritionally diverse of all eukaryotes, include: – Photoautotrophs, which contain chloroplasts – Heterotrophs, which absorb organic molecules or ingest larger food particles – Mixotrophs, which combine photosynthesis and heterotrophic nutrition

7. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 3 Catagories of Protist 1.Photosynthetic Protist: Plant like or Alga 2.Ingestive Protist: Animal like 3.Absorptive Protist: Fungus like

8. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Most protist are aquatic, including freshwater and marine species. But they are diverse in habitat too.

9. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Phytoplankto n Protists are also important constituents for plankton. Phytoplankton is usually at the bottom of a food pyramid for the majority of water species.

10. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Reproduction and life cycles are also highly varied among protists, with both sexual and asexual species

11. LE 28-2 The freshwater ciliate Stentor, a unicellular protozoan (LM) 100 µm Ceratium tripos, a unicellular marine dinoflagellate (LM) 500 µm Delesseria Sanguinea, a multicellular marine red alga Spirogyra, a filamentous freshwater green alga (insert LM) 4 cm

12. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Endosymbiosis in Eukaryotic Evolution There is now considerable evidence that much of protist diversity has its origins in endosymbiosis. Endosymbiosis is were certain unicellular organisms engulf other cells and take over the host and their organelles.

13. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The plastid-bearing (double membrane organelle) lineage of protists evolved into red algae and green algae On several occasions during eukaryotic evolution red and green algae underwent secondary endosymbiosis, in which they were ingested

14. LE 28-3 Cyanobacterium Primary endosymbiosis Secondary endosymbiosis Secondary endosymbiosis Secondary endosymbiosis Heterotrophic eukaryote Red algae Green algae Dinoflagellates Plastid Apicomplexans Stramenopiles Plastid Euglenids Chlorarachniophytes

15. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 28.2: Diplomonads and parabasalids have modified mitochondria A tentative phylogeny of eukaryotes divides eukaryotes into many clades

16. LE 28-4 Alveolata Diplomonadida Parabasala Euglenozoa Ancestral eukaryote Stramenopila Amoebozoa(Opisthokonta) (Viridiplantae) Cercozoa Radiolaria Fungi Animalia Rhodophyta Chlorophyta Plantae Plants Chlorophytes Charophyceans Red algaeMetazoansFungi Choanoflagellates Cellular slime molds Plasmodial slime molds GymnamoebasEntamoebasRadiolarians Chlorarachniophytes Foraminiferans Brown algae Golden algae Oomycetes Diatoms Ciliates Apicomplexans Euglenids Dinoflagellates Kinetoplastids Diplomonads Parabasalids

17. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Diplomonads and parabasalids are adapted to anaerobic environments Both clades lack plastids Their mitochondria do not have DNA, electron transport chains, and citric-acid cycle enzymes

18. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Diplomonad s Diplomonads have two nuclei and multiple flagella

19. LE 28-5a Giardia intestinalis, a diplomonad (colorized SEM ) 5 µm

20. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Parabasalids Parabasalids include trichomonads, which move by means of flagella and an undulating part of the plasma membrane

21. LE 28-5b Flagella Trichomonas vaginalis, a parabasalid (colorized SEM ) Undulating membrane 5 µm

22. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 28.3: Euglenozoans have flagella with a unique internal structure Euglenozoa is a diverse clade that includes predatory heterotrophs, photosynthetic autotrophs, and pathogenic parasites Their main feature distinguishing them as a clade is a spiral or crystalline rod of unknown function inside their flagella

23. LE 28-6 Flagella 0.2 µm Crystalline rod Ring of microtubules

24. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Kinetoplastids: Group of Euglenozoans Kinetoplastids have a single mitochondrion with an organized mass of DNA called a kinetoplast They include free-living consumers of bacteria in freshwater, marine, and moist terrestrial ecosystems, parasite to plants and animals

25. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The parasitic kinetoplastid Trypanosoma causes sleeping sickness in humans spread by the tsetse fly and also Chag’s disease(blood-sucking insects causing heart failure).

26. LE 28-7 9 µm

27. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Euglenids Euglenids have one or two flagella that emerge from a pocket at one end of the cell. Can be autotroph or heterotroph. The glucose polymer paramylon is also characteristic of this clade

28. LE 28-8 5 µm Euglena (LM) Plasma membrane Nucleus Short flagellum Eyespot Light detector Contractile vacuole Chloroplast Paramylon granule Pellicle Long flagellum

29. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 28.4: Alveolates have sacs beneath the plasma membrane Members of the clade Alveolata have membrane-bounded sacs (alveoli) just under the plasma membrane

30. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Dinoflagellates Dinoflagellates are a diverse group of aquatic photoautotrophs and heterotrophs They are abundant components of both marine and freshwater phytoplankton Each has a characteristic shape that in many species is reinforced by internal plates of cellulose Two flagella make them spin as they move through the water

31. LE 28-9 0.2 µm Alveoli Flagellum

32. LE 28-10 3 µm Flagella

33. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Rapid growth of some dinoflagellates is responsible for causing “red tides,” which can be toxic to humans

34. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Apicomplexans Apicomplexans are parasites of animals and some cause serious human diseases One end, the apex, contains a complex of organelles specialized for penetrating a host They have a nonphotosynthetic plastid, the apicoplast Most have sexual and asexual stages that require two or more different host species for completion

35. LE 28-11 Sporozoites (n) Inside mosquito Oocyst Zygote (2n) MEIOSIS Merozoite (n) Liver cell Liver FERTILIZATION Gametes Gametocytes (n) Red blood cells Inside human Merozoite Apex Red blood cell 0.5 µm Haploid (n) Key Diploid (2n) MALARIA

36. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Ciliates Ciliates, a large varied group of protists, are named for their use of cilia to move and feed They have large macronuclei and small micronuclei The micronuclei function during conjugation, a sexual process that produces genetic variation Conjugation is separate from reproduction, which generally occurs by binary fission

37. LE 28-12 FEEDING, WASTE REMOVAL, AND WATER BALANCE CONJUGATION AND REPRODUCTION MEIOSIS MICRONUCLEAR FUSION Haploid micronucleus Diploid micronucleus Diploid micronucleus Contractile vacuole Oral groove Cell mouth Micronucleus Macronucleus 50 µm Thousands of cilia cover the surface of Paramecium. Paramecium, like other freshwater protists, constantly takes in water by osmosis from the hypotonic environment. Bladderlike contractile vacuoles accumulate excess water from radial canals and periodically expel it through the plasma membrane. Paramecium feeds mainly on bacteria. Rows of cilia along a funnel-shaped oral groove move food into the cell mouth, where the food is engulfed into food vacuoles by phagocytosis. Food vacuoles combine with lysosomes. As the food is digested, the vacuoles follow a looping path through the cell. The undigested contents of food vacuoles are released when the vacuoles fuse with a specialized region of the plasma membrane that functions as an anal pore. Compatible mates Two cells of compatible mating strains align side by side and partially fuse. Macronucleus Meiosis of micronuclei produces four haploid micronuclei in each cell. Three micronuclei in each cell disintegrate. The remaining micro- nucleus in each cell divides by mitosis. The cells swap one micronucleus. The cells separate. Key Micronuclei fuse, forming a diploid micronucleus. Conjugation Reproduction Two rounds of cytokinesis partition one maccronucleus and one macronucleus into each of four daughter cells. The original macronucleus disintegrates. Four micronuclei become macronuclei, while the other four remain micronuclei. Three rounds of mitosis without cytokinesis produce eight micronuclei.

38. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 28.5: Stramenopiles have “hairy” and smooth flagella The clade Stramenopila includes several groups of heterotrophs as well as certain groups of algae Most have a “hairy” flagellum paired with a “smooth” flagellum

39. LE 28-13 Smooth flagellum Hairy flagellum 5 µm

40. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Oomycetes (Water Molds and Their Relatives) Oomycetes include water molds, white rusts, and downy mildews They were once considered fungi based on morphological studies. But using evolutionary relationships it shows convergent Most oomycetes are decomposers or parasites They have filaments (hyphae) that facilitate nutrient uptake Their ecological impact can be great, as in Phytophthora infestans causing potato blight

41. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Diatoms are unicellular algae with a unique two-part, glass-like wall of hydrated silica. Reproduce mainly asexually by mitosis. Fossilized diatom walls compose much of the sediments known as diatomaceous earth

42. LE 28-15 3 µm

43. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Diatoms are a major component of phytoplankton and are highly diverse

44. LE 28-16 50 µm Diatom diversity (LM)

45. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Golden Algae Golden algae, or chrysophytes, are named for their color, which results from their yellow and brown carotenoids The cells of golden algae are typically biflagellated, with both flagella near one end Most are unicellular, but some are colonial

46. LE 28-17 25 µm

47. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Brown Algae Brown algae, or phaeophytes, are the largest and most complex algae All are multicellular, and most are marine

48. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Brown algae include many species commonly called seaweeds Seaweeds have the most complex multicellular anatomy of all algae

49. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Parts of Seaweed/Brown Alga: 1.Thallus: seaweed body that is plant- like although it lacks true roots, stems and leaves. 2.Holdfast: rootlike part of seaweed 3.Stipe: support for leaf-like blades 4.Blades: surface for photosynthesis 5.Floats: some have floats that help them to stay at the surface for light

50. LE 28-18 Blade Stipe Holdfast

51. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Giant seaweeds called kelps live in deep parts of the ocean

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53. Human Uses of Seaweeds Many seaweeds are important commodities Many are harvested for food Used to make things smooth or thick (agar and carrageenan/red alga and algin/brown alga)

54. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Alternation of Generations A variety of life cycles have evolved among the multicellular algae The most complex life cycles include an alternation of generations, the alternation of multicellular haploid and diploid forms

55. LE 28-21 Developing sporophyte Zygote (2n) FERTILIZATION Mature female gametophyte (n) Egg Sperm MEIOSIS Haploid (n) Key Diploid (2n) Sporangia Sporophyte (2n) Zoospores Female Gametophytes (n) Male

56. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 28.6: Cercozoans and radiolarians have threadlike pseudopodia A newly recognized clade, Cercozoa, contains species among the organisms called amoebas Amoebas were formerly defined as protists that move and feed by means of pseudopodia Cercozoans are distinguished from most other amoebas by their threadlike pseudopodia

57. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Foraminiferans (Forams) Foraminiferans, or forams, are named for porous, generally multichambered shells, called tests Pseudopodia extend through the pores in the test (hardened with Ca CO 3 ) Foram tests in marine sediments form an extensive fossil record

58. LE 28-22 20 µm

59. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Radiolarians Marine protists called radiolarians have tests fused into one delicate piece, usually made of silica Radiolarians phagocytose microorganisms with their pseudopodia The pseudopodia of radiolarians, known as axopodia, radiate from the central body

60. LE 28-23 200 µm Axopodia

61. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 28.7: Amoebozoans have lobe- shaped pseudopodia Amoebozoans are amoeba that have lobe-shaped, rather than threadlike, pseudopodia They include gymnamoebas, entamoebas, and slime molds

62. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Gymnamoebas Gymnamoebas are common unicellular amoebozoans in soil as well as freshwater and marine environments Most gymnamoebas are heterotrophic and actively seek and consume bacteria and other protists

63. LE 28-24 Pseudopodia 40 µm

64. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Entamoebas Entamoebas are parasites of vertebrates and some invertebrates Entamoeba histolytica causes amebic dysentery in humans

65. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Slime Molds Slime molds, or mycetozoans, were once thought to be fungi Molecular systematics places slime molds in the clade Amoebozoa

66. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Plasmodial Slime Molds Many species of plasmodial slime molds are brightly pigmented, usually yellow or orange

67. LE 28-25 4 cm

68. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings At one point in the life cycle, plasmodial slime molds form a mass called a plasmodium The plasmodium is undivided by membranes and contains many diploid nuclei It extends pseudopodia through decomposing material, engulfing food by phagocytosis

69. LE 28-26 1 mm MEIOSIS Haploid (n) Key Diploid (2n) Zygote (2n) SYNGAMY Feeding plasmodium Mature plasmodium (preparing to fruit) Young sporangium Mature sporangium Spores (n) Stalk Amoeboid cells (n) Germinating spore Flagellated cells (n)

70. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cellular Slime Molds Cellular slime molds form multicellular aggregates in which cells are separated by their membranes Dictyostelium discoideum is an experimental model for studying the evolution of multicellularity

71. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cellular Slime Molds Compared to Plasmodial Slime Molds CELLULAR SLIME MOLDSPLASMODIAL SLIME MOLDS SINGLE MASS OF CYTOPLASM DIVIDED BY MEMRBANES SINGLE MASS OF CYTOPLASM THAT IS UNDIVIDED BY MEMBRANES HAPLOID NUCLEI (DIPLOID ZYGOTE) DIPLOID NUCLEI SEVERAL MITOTIC DIVISIONS WITHOUT CYTOKINESIS MEIOSIS WITH SEVERAL MITOTIC DIVIVSION WITHOUT CYTOKINESIS NO FLAGELLATE STAGEDIVISIONS ARE SYNCHRONOUS FRUITING BODIES SEXUAL REPRODUCTION FRUITING BODIES ASEXUAL REPRODUCTION BY SPORES

72. LE 28-27 600 µm MEIOSIS Haploid (n) Key Diploid (2n) Zygote (2n) SYNGAMY Migrating aggregate Emerging amoeba SEXUAL REPRODUCTION Amoebas Spores (n) Solitary amoebas (feeding stage) ASEXUAL REPRODUCTION Fruiting bodies Aggregated amoebas 200 µm

73. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 28.8: Red algae and green algae are the closest relatives of land plants Over a billion years ago, a heterotrophic protist acquired a cyanobacterial endosymbiont The photosynthetic descendants of this ancient protist evolved into red algae and green algae

74. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Red algae are reddish in color due to an accessory pigment call phycoerythrin, which masks the green of chlorophyll Red algae are usually multicellular; the largest are seaweeds Red algae are the most abundant large algae in coastal waters of the tropics No flagellate stage in life cycle so depend on water for reproduction

75. LE 28-28 Bonnemaisonia hamifera, a filamentous red alga. Dulse (Palmaria palmata). This edible species has a “leafy” form. A coralline alga. The cells walls of corralline algae are hardened by calcium carbonate. Some coralline algae are members of the biological communities called coral reefs.

76. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Green algae are named for their grass-green chloroplasts. They are closely related to land plants. Two main groups: 1.chlorophytes 2.charophyceans

77. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Most chlorophytes live in fresh water, although many are marine Other chlorophytes live in damp soil, as symbionts in lichens, or in snow Chlorophytes include unicellular, colonial, and multicellular forms

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79. LE 28-30 Calperpa, an inter-tidal chlorophyte. The branched filaments lack cross-walls and thus are multinucleate. In effect, the thallus is one huge “supercell.” 50 µm Volox, a colonial freshwater chlorophyte. The colony is a hollow ball whose wall is composed of hundreds or thousands of biflagellated cells (see inset LM) embedded in a gelatinous matrix. The cells are usually connected by strands of cytoplasm; if isolated, these cells cannot reproduce. The large colonies seen here will eventually release the small “daughter” colonies within them (LM). Ulva, or sea lettuce. This edible seaweed has a multicellular thallus differentiated into leaflike blades and a rootlike holdfast that anchors the alga against turbulent waves and tides. 20 µm

80. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Most chlorophytes have complex life cycles with both sexual and asexual reproductive stages

81. LE 28-31 MEIOSIS Haploid (n) Key Diploid (2n) SYNGAMY SEXUAL REPRODUCTION Zoospores ASEXUAL REPRODUCTION Mature cell (n) Zygote (2n) Regions of single chloroplast Nucleus Flagella Cell wall 1 µm

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