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Eukaryotes

Eukaryotes. Protista, Fungi, Plantae, Animalia Complex >10x larger DNA in nucleus Cell membrane Some also have cell wall Membrane bound organelles specialization. Protista. Very diverse mostly unicellular, some colonial, some multicellular (w/simple tissues) Autotrophs Plant-like

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Eukaryotes

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  1. Eukaryotes • Protista, Fungi, Plantae, Animalia • Complex • >10x larger • DNA in nucleus • Cell membrane • Some also have cell wall • Membrane bound organelles • specialization

  2. Protista • Very diverse • mostly unicellular, some colonial, some multicellular (w/simple tissues) • Autotrophs • Plant-like • Heterotrophs • Animal-like protozoans • Fungal-like • Mixotrophs • Photoautotrophic and heterotrophic pathways • Aquatic or moist environments

  3. Protistan origin • Eukaryotes that share some Archaea characteristics (e.g. biochemistry & genetics) • Lacks the peptidoglycons in cell walls of bacteria • Otherwise varies in modes of Eukarya reproduction, locomotion, & morphology • Endocytosis; 1o endosymbiosis with prokaryotes (Fig 28.2) • 2o endosymbiosis: heterotroph engulfing red or green algae

  4. “…protist phylogeny continues to emerge…changing rapidly…”(Campbell 28.1) • Five Supergroups: • Excavata • Chromalveolata • Rhizaria • Archaeplastida • Unikonta

  5. Diplomonads Parabasalids Euglenozoans Figure 28.3a Excavata Dinoflagellates Apicomplexans Ciliates Diatoms Golden algae Brown algae Oomycetes Alveolates Chromalveolata Stramenopiles Cercozoans Forams Radiolarians Rhizaria Red algae Chlorophytes Charophytes Land plants Greenalgae Archaeplastida Slime molds Gymnamoebas Entamoebas Nucleariids Fungi Choanoflagellates Animals Amoebozoans Unikonta Opisthokonts

  6. “…it may be helpful to focus less on the specific names of groups of organisms and more on why the organisms are important…” (Campbell 28.1) Functionally… “Animal-like” Protozoans heterotrophic consumers “Fungi-like” Protists share fungal characteristics; many moved back/forth from Fungi “Plant-like” Algae non-plant, photosynthetic aquatic eukaryotes

  7. Diplomonads (Excavata clade – 8 ed.) • Spore forming • Two nuclei • Multiple flagella • Usually anaerobic • Due to their modified mitochondria that lack ETCs & the use of O2 in respiration • E.g. Giardia • Intestinal parasite • Contaminates streams • Causes severe diarrhea

  8. Kinetoplast DNA in mitochondria E.g. Trypanosoma Blood parasite Single encased flagellum African Tsetse fly Sleeping sickness (attacks nervous system; lethargy; death if untreated) So.Amer. Kissing bugs Chagas disease Kinetoplastids(Excavata clade – 8 ed.)

  9. Pseudopodia extensions of the cell Locomotion Feeding Various environments Aquatic; parasitic; moist soils Various morphology Amoeboids

  10. Animal-like protists Heterotrophs Unicellular or colonial Various forms Foraminiferans Have a CaCO3 shell Thin extended pseudopods Planktonic or benthic Adds to the calcareous sediments Radiolarians Silica shells; thin pseudopods; planktonic; silicious sediments Ciliates Use of cilia to feed and move Stalked, colonial, or “free-swimming” Protozoans

  11. Cilia to move and feed E.g. Paramecium, Stentor, Vorticella Contractile vacuole osmoregulation Two nuclei types Macronucleus Everyday activities Micronuclei Sexual reproduction Ciliates

  12. Parasites Apex structures for penetrating host cells Lack cilia, flagella, or pseudopods E.g. Plasmodium Malaria Enters and feeds on red blood cells Vector = ♀ mosquitoes Apicomplexans

  13. Two flagella in grooves Spinning flagellates Phytoplankton Photosynthesizing aquatic species Red tides red pigments along with chl a Some are toxic Shell fish accumulation Bioluminescence Dinoflagellates

  14. Phytoplankton Silica cell wall Glass-like Two halves like a petri plate Mitotically divide the halves Secretes the smaller half Nucleus triggers meiosis when too small Diatoms

  15. Diatom reproduction

  16. Chrysophyta Silicoflagellates Star shaped; silicon Desmids Pectin & silican walls Golden or yellow Coccolithorids Calcium carbonate coccoliths All are important planktonic 1o producers Emiliania huxleyi (E. huxleyi)

  17. More photoautotrophic protistans… known as: Algae, seaweed, kelp Thalli may be filamentous, grow in mats or crusts, sheets, or kelp “ Plant-like” primary producers, but not plants: Lack true leaves, stems & roots Organized by pigment variations Phaeophyta (browns) Rhodophyta (reds) Chlorophyta (greens) Multicellular Protists (algae)

  18. Current phylogeny of the 5 supergroups of Eukaryotes See also: Summary Table on page 598 of text (Ch 28)

  19. Brown/yellow pigment Fucxanthin, some phycobilin, some carotenoids (& chl) Diverse morphologies Simple, small individual to large & complex (i.e. lengths up to 100m) kelp forest communities Some exhibit rapid growth 1 to 2 feet a day Important source of algin Thickener, stabilizer, emulsifier in many products Phaeophyta

  20. Red pigments Phycoerythrin, Phycobilins, carotenoids As a group, expands to greater depths than other algae Why? Coralline algae CaCO3 in cell walls Defense and structure Important component of coral reef environments Filamentous or Encrusting Important component of coral reef environments Commercial uses Source of carrageenan & agar (emulsifiers & gel thickeners) Food Nori (sushi wraps) from Porphyra Rhodophyta

  21. Green pigments Chl a & Chl b Same as plants Diverse morphologies Filamentous Sheets Spongy Calcareous Important component of coral reef environments Chlorophyta

  22. Colonial plant-like chloroplasts Volvox Ulothrix Spyrogyra Other Chlorophytan examples

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