1. Kingdom Protista Chapter 20

2. A dense forest grows along the west coast of North America from Mexico to Alaska. The photosynthetic giants in this forest reach heights of 50 meters (160 feet). Nearly 100 species of invertebrate and vertebrate animals live in the forest, and many other species visit the forest to feed or to escape predators.

3. LEARNING OBJECTIVE 1 Briefly describe the features common to the members of the kingdom Protista Briefly describe the features common to the members of the kingdom Protista

4. Kingdom Protista Composed of “simple” eukaryotic organisms Composed of “simple” eukaryotic organisms Most are aquatic Most are aquatic Protists exhibit remarkable diversity Protists exhibit remarkable diversity Range in size from single cells to large multicellular organisms Range in size from single cells to large multicellular organisms

5. Protists

6. (a) Various protists in a drop of pond water. Cilia Didinium Paramecium Flagellum Euglena Pseudopod Amoeba Fig. 20-1a, p. 384

7. Flagella (b) Chlamydomonas, a unicellular, photosynthetic protist, is a motile organism with two flagella and a cup-shaped chloroplast. Starch granule Chloroplast Nucleus Cell wall Fig. 20-1b, p. 384

8. LEARNING OBJECTIVE 2 Discuss in general terms the diversity in the protist kingdom, including means of locomotion, modes of nutrition, interactions with other organisms, and modes of reproduction Discuss in general terms the diversity in the protist kingdom, including means of locomotion, modes of nutrition, interactions with other organisms, and modes of reproduction

9. Means of Locomotion 1 Most protists have some means of locomotion, at least for part of the life cycle Most protists have some means of locomotion, at least for part of the life cycle Some are nonmotile Some are nonmotile

10. Means of Locomotion 2 Some protists move by Some protists move by pushing out cytoplasmic extensions pushing out cytoplasmic extensions flexing individual cells flexing individual cells waving cilia waving cilia lashing flagella lashing flagella

11. Modes of Nutrition and Interactions with Other Organisms Protists obtain nutrients photosynthetically or heterotrophically Protists obtain nutrients photosynthetically or heterotrophically Protists may be free-living or form symbiotic relationships Protists may be free-living or form symbiotic relationships Range from mutualism to parasitism Range from mutualism to parasitism

12. Modes of Reproduction Almost all protists reproduce asexually Almost all protists reproduce asexually Many reproduce both sexually and asexually Many reproduce both sexually and asexually

13. LEARNING OBJECTIVE 3 Describe the kinds of data biologists use to classify eukaryotes Describe the kinds of data biologists use to classify eukaryotes

14. Evidence of Phylogenetic Relationships 1 Molecular data Molecular data For gene that codes for small subunit ribosomal RNA in different eukaryotes For gene that codes for small subunit ribosomal RNA in different eukaryotes For other nuclear genes (many of which code for proteins) in various protists For other nuclear genes (many of which code for proteins) in various protists

15. Evidence of Phylogenetic Relationships 2 Ultrastructure Ultrastructure Fine details of cell structure revealed by electron microscopy Fine details of cell structure revealed by electron microscopy Often similar among protists that comparative molecular evidence suggests are monophyletic and evolved from a common ancestor Often similar among protists that comparative molecular evidence suggests are monophyletic and evolved from a common ancestor

16. Relationships Among Eukaryotes

17. Ancestral eukaryote Fung Animals Cellular slime molds Plasmodial slime molds Land plants Green algae Red algae Brown algae Golden algaeDiatomsWater molds Dinoflagellates EuglenoidsSome zooflagellates Fig. 20-2, p. 386

18. LEARNING OBJECTIVE 4 Briefly describe and compare euglenoids and dinoflagellates Briefly describe and compare euglenoids and dinoflagellates

19. KEY TERMS EUGLENOID EUGLENOID A mostly freshwater, flagellated, unicellular protist that moves by an anterior flagellum and is usually photosynthetic A mostly freshwater, flagellated, unicellular protist that moves by an anterior flagellum and is usually photosynthetic

20. Euglenoids

21. (a) A living species of Euglena. (b) Euglena has an eyespot, a light-sensitive organelle that helps it react to light. Pellicle Paramylon body (stored food) Nucleus Chloroplast Contractile vacuole Eyespot Flagellum for locomotion Nonemergent flagellum Eyespot Mitochondria (indistinguishable in photo) Nucleolus Chromatin Fig. 20-3, p. 388

22. (a) A living species of Euglena. (b) Euglena has an eyespot, a light-sensitive organelle that helps it react to light. Pellicle Nonemergent flagellum Mitochondria (indistinguishable in photo) Nucleolus Chromatin Flagellum for locomotion Eyespot Contractile vacuole Chloroplast Nucleus Paramylon body (stored food) Fig. 20-3, p. 388 Stepped Art

23. KEY TERMS DINOFLAGELLATE DINOFLAGELLATE A unicellular, biflagellated, typically marine protist that is usually photosynthetic, contains the brown pigment fucoxanthin, and is an important component of plankton A unicellular, biflagellated, typically marine protist that is usually photosynthetic, contains the brown pigment fucoxanthin, and is an important component of plankton

24. Dinoflagellates

25. Diatoms. The varied and intricate shapes of diatoms are due to the cells’ silica-containing cell walls, or frustules. This scanning electron micrograph of a diatom shows the numerous pores in its frustule.

26. Mixed marine diatoms from the ocean floor. These unicellular photosynthetic algae usually have walls of silica which resist decomposition and large deposits known as diatomaceous earth have many industrial uses. SEM X2800. Credit: © Science VU/Visuals Unlimited 171148

27. Dinoflagellate displays. (a) A “red tide” is caused by the rapid growth of dinoflagellate populations in coastal waters. (b) Mosquito Bay in Puerto Rico is well known for its displays of bioluminescence, which are produced when the water is disturbed.

28. LEARNING OBJECTIVE 5 Briefly describe and compare water molds, diatoms, golden algae, and brown algae Briefly describe and compare water molds, diatoms, golden algae, and brown algae

29. KEY TERMS WATER MOLD WATER MOLD A protist with a body consisting of a coenocytic mycelium and with asexual reproduction by motile zoospores and sexual reproduction by oospores A protist with a body consisting of a coenocytic mycelium and with asexual reproduction by motile zoospores and sexual reproduction by oospores

30. Water Molds

31. Primary zoospore (pear shaped) Encysted primary zoospore Secondary zoospore (bean shaped) Encysted secondary zoospore Germination of the zoospore Saprolegnia reproduces asexually by forming zoospores within zoosporangium. ASEXUAL REPRODUCTION (by mitosis) Zoospores Zoosporangium Mycelium SEXUAL REPRODUCTION DIPLOID (2n) GENERATION HAPLOID (n) GENERATION Germination of oospore After fertilization, oospores develop from fertilized oospheres. Each oospore may develop into new mycelium. Oospores Fertilization Sperm nuclei move into oospheres. Oospheres within oogonium Meiosis results in haploid sperm nuclei within antheridia and haploid oospheres (eggs) within oogonia. Meiosis Antheridium (male reproductive structure) Saprolegnia reproduces sexually by antheridia and oogonia. Oogonium (female reproductive structure) 2 1 3 4 5 Fig. 20-5, p. 390

32. KEY TERMS DIATOM DIATOM Usually a unicellular protist, covered by an ornate siliceous shell and containing the brown pigment fucoxanthin, that is an important component of plankton in both marine and fresh water Usually a unicellular protist, covered by an ornate siliceous shell and containing the brown pigment fucoxanthin, that is an important component of plankton in both marine and fresh water

33. Diatoms

34. KEY TERMS GOLDEN ALGA GOLDEN ALGA A protist that is biflagellated, unicellular, and photosynthetic and contains the brown pigment fucoxanthin A protist that is biflagellated, unicellular, and photosynthetic and contains the brown pigment fucoxanthin BROWN ALGA BROWN ALGA A predominantly marine, photosynthetic protist that is multicellular and contains the brown pigment fucoxanthin A predominantly marine, photosynthetic protist that is multicellular and contains the brown pigment fucoxanthin

35. Golden Algae

36. Brown Algae

37. a) Laminaria is a typical brown alga. Note the blade, stipe, and holdfast. Holdfast Stipe Blade Fig. 20-8a, p. 393

39. Brown Algae

41. A sea urchin at the base of a kelp forest. A sea otter resting in kelp blades.

42. LEARNING OBJECTIVE 6 Explain why red algae, green algae, and land plants are considered a monophyletic group Explain why red algae, green algae, and land plants are considered a monophyletic group

43. KEY TERMS RED ALGA RED ALGA One of a diverse group of photosynthetic protists that contain the pigments phycocyanin and phycoerythrin One of a diverse group of photosynthetic protists that contain the pigments phycocyanin and phycoerythrin GREEN ALGA GREEN ALGA One of a diverse group of protists that contain the same pigments as land plants (chlorophylls a and b and carotenoids) One of a diverse group of protists that contain the same pigments as land plants (chlorophylls a and b and carotenoids)

44. Red Algae

45. Green Algae

46. Red and Green Algae Ultrastructure (specifically, similarities in the inner and outer chloroplast membranes) and molecular data support the hypothesis that red algae, green algae, and land plants are monophyletic Ultrastructure (specifically, similarities in the inner and outer chloroplast membranes) and molecular data support the hypothesis that red algae, green algae, and land plants are monophyletic

47. Reproduction in Green Algae Isogamy Isogamy Anisogamy Anisogamy Oogamy Oogamy

48. Volvox aureus is a type of green algae that exist as a spherical colony. Volvox reproduce both sexually and asexually. LM. Credit: © Carolina Biological/Visuals Unlimited 318169

49. Volvox aureus colony. Credit: © Carolina Biological/Visuals Unlimited 311727

50. Life Cycle: Chlamydomonas

51. Four haploid cells emerge, two (+) and two (-). Meiosis occurs. Zygote (2n) Fertilization DIPLOID (2n) GENERATION The (+) and (-) gametes fuse, forming a diploid zygote. from a different strain Gametes are produced by mitosis. Zoospores Both mating types reproduce asexually by mitosis; only (-) strain is shown. HAPLOID (n) GENERATION SEXUAL REPRODUCTION ASEXUAL REPRODUCTION (by mitosis) + + + + - - - - - -- - - - 2 1 3 4 5 Fig. 20-12, p. 397

52. Life Cycle: Ulva

53. 2 1 3 4 Meiosis Fertilization DIPLOID (2n) GENERATION HAPLOID (n) GENERATION Mature diploid alga Motile zygote Gametes fuse, forming zygote, which attaches to substrate and develops into multicellular individual. Male and female algae produce biflagellated gametes by mitosis. Anisogamous gametes Gamete Mature haploid alga Each zoospore develops into multicellular male or female individual. Special cells in diploid alga undergo meiosis to form haploid zoospores. Fig. 20-13, p. 398

54. Conjugation

55. Cells round up and grow conjugation tubes Tubes Nonreproductive cells Fig. 20-14, p. 399

56. LEARNING OBJECTIVE 7 Briefly describe and compare plasmodial slime molds and cellular slime molds Briefly describe and compare plasmodial slime molds and cellular slime molds

57. KEY TERMS PLASMODIAL SLIME MOLD PLASMODIAL SLIME MOLD A protist whose feeding stage consists of a multinucleate, amoeboid plasmodium A protist whose feeding stage consists of a multinucleate, amoeboid plasmodium CELLULAR SLIME MOLD CELLULAR SLIME MOLD A protist whose feeding stage consists of a unicellular, amoeboid organism that aggregates to form a pseudoplasmodium during reproduction A protist whose feeding stage consists of a unicellular, amoeboid organism that aggregates to form a pseudoplasmodium during reproduction

58. Plasmodial Slime Mold

59. Cellular Slime Mold

60. (a) The fruiting body releases spores, each of which gives rise to an amoeba-like organism. Slime mold amoebas ingest food, grow, and reproduce by cell division. After their food is depleted, the cells aggregate and organize into a sluglike pseudoplasmodium that migrates for a period before forming a stalked fruiting body, and the cycle continues. Slug forms Slug differentiates Aggregation Slime mold amoebas Spores Fruiting body 2 1 3 4 5 Fig. 20-16a, p. 400

61. Cellular Slime Mold

63. Animation: Cellular Slime Mold Life Cycle CLICK TO PLAY