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Ch.28   eukaryotic diversity
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Ch.28 eukaryotic diversity

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    Ch.28   eukaryotic diversity Ch.28 eukaryotic diversity Presentation Transcript

    • The Origins of Eukaryotic Diversity Chapter 28
    • Protists• 1st eukaryotes• Protists lived 2 billion years before the evolution of plants, fungi & animals• Most diverse group of eukaryotes• Live anywhere there is water• Protists could include as many as 20 kingdoms
    • Definition of Protists• Mostly single-cellular• Some colonial and multicellular• Eukaryotic
    • Protist Nutrition• Aerobic, use mitochrondria• Can be – Photoautotrophs (algae) – Heterotrophs (protozoa) – Mixotrophs
    • Protist Motility• Cilia or flagella – Most have one at some point in life – 9+2 arrangement of microtubules
    • Trends toward the evolution of eukaryotes• Multicellular prokaryotes• Prokaryotic communities• Compartmentalization of functions within cell
    • Serial Endosymbiosis
    • Secondary Endosymbiosis
    • A hypothetical history of plastids in the photosynthetic eukaryotes
    • Traditional hypothesis for how the three domains of life are related
    • An alternative hypothesis for how the three domains of life are related
    • The kingdom Protista problem
    • A tentative phylogeny of eukaryotes
    • Evolution of Multicellularity• Eukaryotes – Organization allowed for development of more complex structures – Opportunities to specialize & adapt• Multicellularity evolved several times – Multicellular algae (seaweeds) – Ancestors of plants, fungi & animals
    • Survey of Protistan Diversity
    • Diplomonadida & Parabasala• Lack mitochondria Giardia lamblia Trichomonas vaginalis
    • Euglenazoa• Photosynthetic & heterotrophic flagellates
    • Alveolata: unicellular protists w/ subcellular cavities• Dinoflagellates
    • Alveolata: unicellular protists w/ subcellular cavities• Apicomplexans
    • Alveolata: unicellular protists w/ subcellular cavities• Ciliates
    • Ciliates: Stentor (left), Paramecium (right)
    • Conjugation and genetic recombination in Paramecium caudatum
    • Stramenopila: Water molds & Heterokont algae “hairy” flagella• Oomycota (water molds) – Resemble fungi (but not closely related) – Cell walls made of cellulose – Diploid life cycle
    • The life cycle of a water mold
    • Stramenopila: Water molds & Heterokont algae “hairy” flagella• Heterokont algae – 3-membraned plastids – Types • Diatoms • Golden algae • Brown algae
    • Stramenopila: Water molds & Heterokont algae “hairy” flagella• Diatoms – Box-like silica walls – Freshwater & marine plankton
    • Stramenopila: Water molds & Heterokont algae “hairy” flagella• Golden algae• (Chrysophyta) – Yellow and brown pigments • (carotene and xanthophyll) – Can form resistant cysts
    • Stramenopila: Water molds & Heterokont algae “hairy” flagella• Brown algae (Phaeophyta) – Largest & most complex algae – Brown pigments
    • Alternation of Generations
    • Rhodophyta: Red Algae• Lack flagella• Phycoerythrin – red pigment (a phycobilin)• Can absorb light in deep water• Most are marine
    • Chlorophyta: Green Algae• Share common ancestor with plants• Most are freshwater• Unicellular, colonial & multicellular species• Some are seaweeds• Form lichens
    • Protists that Use Pseudopodia• Rhizopods (amoebas) – Move and feed w/ psuedopodia• Actinopods – Axopodia help cell float and feed by phagocytosis• Foraminferans – Porous, calcareous shells – Cytoplasmic strands extend through pores and function in swimming, shell formation & feeding
    • Use of pseudopodia for feeding: Amoeba
    • Actinopods: Heliozoan (left), radiolarian (right)
    • Foraminiferan
    • Mycetozoa: Slime Molds• Resemble fungi b/c of convergent evolution (not actually related)• Plasmodial slime molds – Heterotrophic – Grow on rotting plant material – Feeding stage is called a plasmodium • Multinucleate amoeboid mass• Cellular slime molds – Feeding stage: haploid amoeboid cells – In absence of food: form a slug-like mass
    • Plasmodial slime mold
    • Figure 28.29 The life cycle of a plasmodial slime mold, such as Physarum
    • The life cycle of a cellular slime mold (Dictyostelium)