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Protista

Protista. Eukaryotic Kingdoms. Animalia multicellular, motile, ingestive heterotrophs Fungi multicellular, filamentous, absorptive heterotrophs Plantae multicellular, embryophytic, photoautotrophs. Eukaryotic Kingdoms. Protista non-animal, non-fungal, non-plant eukaryotes

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Protista

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  1. Protista

  2. Eukaryotic Kingdoms • Animalia • multicellular, motile, ingestive heterotrophs • Fungi • multicellular, filamentous, absorptive heterotrophs • Plantae • multicellular, embryophytic, photoautotrophs

  3. Eukaryotic Kingdoms • Protista • non-animal, non-fungal, non-plant eukaryotes • mostly unicellular • several distinct lineages • modern representatives of earliest eukaryotic lineage(s)

  4. non-plantFigure 28-1 non-animal

  5. Eukaryotic Origins • The modern eukaryotic cell type probably arose in stages • a proto-eukaryote arose from a prokaryotic ancestor • the rigid cell surface was replaced with a flexible cell surface • increased surface area for exchange of materials with environment • pseudo-internal membranes for localized metabolism

  6. early “internal” membranesFigure 28-2

  7. Eukaryotic Origins • The modern eukaryotic cell probably arose in stages. • the rigid cell surface was replaced with a flexible cell surface • internalized cell membranes formed the nuclear envelope • digestive endocytosis increased the capacity for resource uptake

  8. Eukaryotic Origins • The modern eukaryotic cell probably arose in stages. • the rigid cell surface was replaced with a flexible cell surface • origin of a cytoskeleton • required proteins not encoded in modern Bacteria or Archaea genomes • produced the diversity of morphology and motility in unicellular eukaryotic cell types

  9. Eukaryotic Origins • The modern eukaryotic cell probably arose in stages. • the origin of organelles by endosymbiosis • peroxisomes detoxify products of oxygen metabolism • mitochondria provide heterotrophic energy generation using oxygen • a few eukaryotes lack mitochondria

  10. two eukaryotes that lack mitochondriaFigure 28-10

  11. Eukaryotic Origins • The modern eukaryotic cell probably arose in stages. • origin of organelles by endosymbiosis • chloroplasts provide an autotrophic energy/carbon source and generate oxygen

  12. Figure 28-3

  13. Modern Eukaryotes • General characters of modern protists • inhabit aquatic or damp sites • exhibit diverse structures • utilize multiple nutritional modes (but fewer than prokaryotes) • “protozoans” (a polyphyletic group) • ingestive heterotrophs • “algae” (a polyphyletic group) • photoautotrophs

  14. Amoeba proteusFigure 28-4

  15. Modern Eukaryotes • General characters of modern protists • locomotion • none • amoeboid • pseudopods structured by cytoskeletons • ciliary • provides fast & precise movement

  16. ciliate diversityFigure 28-15

  17. Modern Eukaryotes • General characters of modern protists • locomotion • none • amoeboid • pseudopods structured by cytoskeletons • ciliary • provides fast & precise movement • flagellar • whiplike movement pushes/pulls cells

  18. twoflagellated protistsFigure 28-11

  19. food vacuole in ParameciumFigure 28-6

  20. Modern Eukaryotes • General characters of modern protists • various vesicles • food vacuole • contractile vacuole

  21. contractile vacuoles expel excess waterFigure 28-5

  22. calcareous shells of foraminiferaFigure 28-7

  23. Modern Eukaryotes • General characters of modern protists • diverse cell surfaces • plasma membrane only • plant-like cell wall • calcium carbonate-reinforced shell • aggregated sand particles • proteinaceous pellicle • glassy silicate shells

  24. transparent glassy shells on radiolariansfigure 28.8

  25. Endosymbiosis • mitochondria and chloroplasts are descended from endosymbiotic proteobacteria and cyanobacteria • 2-membrane envelopes • incomplete, but functional, genomes • incapable of extracellular existence

  26. protists in a protistFigure 28-8

  27. Endosymbiosis • modern radiolarians • contain endosymbiont protists that are potentially free-living organisms • haptophytes, euglenoids, stramenopiles • have chloroplasts with 3 membranes • dinoflagellates & cryptomonads • have chloroplasts with 4 membranes

  28. Figure 28-29

  29. Modern Protists • Life Cycles • asexual or sexual reproduction • asexual reproduction with genetic recombination • Asexual reproduction • binary fission • multiple fission • budding • sporulation

  30. Modern Protists • Life Cycles • sexual reproduction • gametogenic meiosis [animal-like] • sporogenic meiosis [plant-like]

  31. Protist Phylogenies • The protists are not a monophyletic group • several monophyletic groups are being defined among the protists • rRNA sequencing • the significance of morphological, metabolic, life cycle characters is being evaluated

  32. aphylogeny of protist groupsFigure 28-9

  33. Diplomonads & Parabasalids • oldest known clade(s) of protists • lack mitochondria (secondary reduction?) • some cause human diseases • Giardia lamblia - a diplomonad • Trichomonas - a parabasilid

  34. Protist Phylogenies • The Euglenozoa • unicellular, asexual flagellates • Euglenoids • complex cellular organization • two unequal anterior flagella • +/- chloroplasts (3 membrane envelope) • able to grow autotrophically or heterotrophically

  35. photosynthetic euglenoidFigure 28-11

  36. Protist Phylogenies • The Euglenozoa • Kinetoplastids • have a single large mitochondrion • with DNA in a kinetoplast • DNA minicircles & maxicircles • maxicircles encode proteins • minicircles encode editorial guides • includes many pathogens • sleeping sickness, leishmaniasis, etc.

  37. parasitic kinetoplastidFigure 28-12

  38. Protist Phylogenies • The Alveolata • Dinoflagellates [Pyrrophyta] • unicellular, mostly marine, mostly photosynthetic • two flagella in perpendicular grooves • common endosymbionts esp. in sponges • some secondarily heterotrophic parasites • some cause red tides • many are bioluminescent

  39. Dinoflagellate red tideFigure 28-13

  40. Protist Phylogenies • The Alveolata • Apicomplexans • obligate parasites • complex life cycles • asexual and sexual reproduction • two or more hosts

  41. Figure 28-14

  42. Protist Phylogenies • The Alveolata • Ciliates • possess short, hair-like cilia • mostly heterotrophic • highly specialized body form • possess two types of nuclei • 1-1000 macronuclei - expression • 1-80 micronuclei - recombination

  43. CiliatesFigure 28-15

  44. ParameciumFigure 28-16

  45. Protist Phylogenies • The Alveolata • Ciliates • Paramecium - genetic recombination without reproduction • conjugation recombines the genomes of two cells • reproduction does not accompany conjugation • non-conjugating clones eventually die

  46. Paramecium conjugation Figure 28-17

  47. Protist Phylogenies • The Stramenopiles • protists bearing two unequal flagella, one with tubular hairs (and their descendants) • two photosynthetic groups, one heterotrophic group • the “brown plant” kingdom

  48. DiatomsFigure 28-18

  49. Protist Phylogenies • The Stramenopiles • Diatoms [Bacillariophyta] • single-celled, non-flagellated • produce chrysolaminarin and oils • many produce cell walls containing silica • asexual reproduction reuses cell walls • sexual reproduction creates new walls

  50. diatom reproductionFigure 28-19

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