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Endosymbiosis --> Eukaryotic Evolution
Plastid Dinoflagellates Secondary endosymbiosis Apicomplexans Cyanobacterium Red alga Primary endosymbiosis Stramenopiles Heterotrophic eukaryote Plastid Secondary endosymbiosis Figure 28.2 Diversity of plastids produced by secondary endosymbiosis Over the course of evolution, this membrane was lost. Euglenids Secondary endosymbiosis Green alga Chlorarachniophytes
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Protist Diversity Figure 28.3 Protist diversity
Diplomonads Parabasalids Excavata Euglenozoans Dinoflagellates Alveolates Apicomplexans Ciliates Diatoms Chromalveolata Golden algae Stramenopiles Brown algae Oomycetes Chlorarachniophytes Forams Rhizaria Radiolarians Red algae Chlorophytes Green algae Archaeplastida Figure 28.3 Protist diversity For the Cell Biology Video Demonstration of Chemotaxis, go to Animation and Video Files. Charophyceans Land plants Slime molds Amoebozoans Gymnamoebas Entamoebas Nucleariids Unikonta Fungi Opisthokonts Choanoflagellates Animals
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Protist Diversity - Diplomonads intestinal parasites
Figure 28.3 Protist diversity 5 µm
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Diatoms - unicellular algae / cell walls are glass-like and made of silica
Figure 28.3 Protist diversity 50 µm
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Forams - have porous shells called tests
Figure 28.3 Protist diversity
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Volvox - colonial freshwater chlorophytes
20 µm 50 µm Figure 28.3 Protist diversity
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Amoeba - have pseudopods for ingestion and motility
Figure 28.3 Protist diversity 100 µm
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Flagella Undulating membrane 5 µm
Trichomonas vaginali Parabasalids that commonly inhabit the female vagina Flagella Figure 28.4 The parabasalid Trichomonas vaginalis (colorized SEM) Undulating membrane 5 µm
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Euglenozoans Flagella 0.2 µm Crystalline rod inside flagella
Figure 28.5 Euglenozoan flagellum Crystalline rod inside flagella Ring of microtubules
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9 µm Trypannnosoma - the Kinetoplastid that causes Sleeping Sickness
Figure 28.6 Trypanosoma, the kinetoplastid that causes sleeping sickness 9 µm
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Euglenids can be both autotrophic and heterotrophic
Long flagellum Eyespot Short flagellum Light detector Adaptation for photosynthesis Contractile vacuole osmoregulation Nucleus Chloroplast Figure 28.7 Euglena, a euglenid commonly found in pond water Plasma membrane Pellicle Protein bands beneath plasma membrane Provide strength and Flexibility. Euglena (LM) 5 µm
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Dinoflagellates some are bioluminescent /cause “Red Tides”
Flagellum Alveoli - sacs under the plasma membrane Alveolate Figure 28.8 Alveoli 0.2 µm
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Two host life cycle of Plasmodium - causes malaria
Inside mosquito Inside human Merozoite Sporozoites (n) Liver Liver cell Oocyst Apex MEIOSIS Red blood cell Merozoite (n) 0.5 µm Zygote (2n) Red blood cells Figure The two-host cycle of Plasmodium, the apicomplexan that causes malaria FERTILIZATION Gametes Gametocytes (n) Key Haploid (n) Diploid (2n)
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Paramecium Contractile vacuole Oral groove Cell mouth Cilia 50 µm Micronucleus Food vacuoles Macronucleus (a) Feeding, waste removal, and water balance MEIOSIS Haploid micronucleus Diploid micronucleus Compatible mates Figure Structure and function in the ciliate Paramecium caudatum The original macronucleus disintegrates. Diploid micronucleus MICRONUCLEAR FUSION Key ConjugationReproduction (b) Conjugation and reproduction
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3 µm Freshwater Diatom with glass-like wall of silica
Figure A freshwater diatom (colorized SEM) 3 µm
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Flagellum Outer container Living cell 25 µm Colonial Golden Algae
Figure Dinobryon, a colonial golden alga found in fresh water (LM) 25 µm
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Brown Algae Blade Stipe Holdfast
Figure Seaweeds: adapted to life at the ocean’s margins Holdfast
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Brown Algae Alternation of Generations
Sporangia 10 cm MEIOSIS Sporophyte (2n) Zoospore Female Developing sporophyte Figure The life cycle of the brown alga Laminaria: an example of alternation of generations Gametophytes (n) Zygote (2n) Mature female gametophyte (n) Male Egg FERTILIZATION Key Sperm Haploid (n) Diploid (2n)
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Life Cycle of Oomycetes = Water Mold
Oogonium Germ tube Egg nucleus (n) Cyst Antheridial hypha with sperm nuclei (n) MEIOSIS Hyphae ASEXUAL REPRODUCTION Zoospore (2n) FERTILIZATION Zygote germination Zygotes (oospores) (2n) SEXUAL REPRODUCTION Zoosporangium (2n) Key Haploid (n) Diploid (2n) Figure The life cycle of a water mold
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Radiolarian Protist Figure A radiolarian Pseudopodia 200 µm
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Bonnemaisonia hamifera 8 mm
Red Algae : This species has a delicate filamentous form Bonnemaisonia hamifera Figure Red algae 8 mm
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Dulse (Palmaria palmata)
Red Algae: This leafy species is edible 20 cm Figure Red algae Dulse (Palmaria palmata)
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Nori. The red alga Porphyra is the
source of a traditional Japanese food. The seaweed is grown on nets in shallow coastal waters. The harvested seaweed is spread on bamboo screens to dry. Figure Red algae Paper-thin, glossy sheets of nori make a mineral-rich wrap for rice, seafood, and vegetables in sushi.
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Green Algae Ulva, or sea lettuce edible seaweed 2 cm (b) Caulerpa, an
Figure Multicellular chlorophytes (b) Caulerpa, an intertidal chloro- phyte
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Most chlorophytes have complex life cycles with both sexual and asexual reproductive stages:
Flagella – 1 µm Cell wall + Gamete (n) – + Nucleus Zoospore Mature cell (n) FERTILIZATION ASEXUAL REPRODUCTION SEXUAL REPRODUCTION Zygote (2n) Cross section of cup-shaped chloroplast Figure The life cycle of Chlamydomonas, a unicellular chlorophyte Key MEIOSIS Haploid (n) Diploid (2n)
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Eukaryotes Choanoflagellates Animals Unikonta Fungi Common ancestor
of all eukaryotes Amoebozoans Diplomonads Excavata Euglenozoans Alveolates Chromalveolata Stramenopiles Figure What is the root of the eukaryotic tree? DHFR-TS gene fusion Rhizarians Rhizaria Red algae Green algae Archaeplastida Plants
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Life Cycle of Plasmodial Slime Mold
4 cm FERTILIZATION Zygote (2n) Feeding plasmodium Mature plasmodium (preparing to fruit) Flagellated cells (n) Young sporangium Amoeboid cells (n) Mature sporangium Germinating spore Spores (n) Figure The life cycle of a plasmodial slime mold MEIOSIS 1 mm Stalk Key Haploid (n) Diploid (2n)
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Life Cycle of Cellular Slime Mold
Spores (n) FERTILIZATION Emerging amoeba (n) Zygote (2n) SEXUAL REPRODUCTION Solitary amoebas (feeding stage) (n) 600 µm MEIOSIS Fruiting bodies (n) ASEXUAL REPRODUCTION Amoebas (n) Aggregated amoebas Migrating aggregate Figure The life cycle of Dictyostelium, a cellular slime mold Key Haploid (n) Diploid (2n) 200 µm
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Protist Symbiont ++ Figure A protist symbiont 10 µm
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Nurseries with P. ramorum infections (2004) on
Risk Map for the Parasitic Protist Sudden Oak Death in United States Key Figure Risk map for sudden oak death in the contiguous United States High risk Moderate risk Low risk Nurseries with P. ramorum infections (2004) on other host plants (such as rhododendron).
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Protists are Key Producers in Aquatic Communities
Other consumers Herbivorous plankton Carnivorous plankton Bacteria absorbed by Figure Protists are key producers in aquatic communities Soluble organic matter Protistan producers secrete
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Review
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You should now be able to:
Explain why the kingdom Protista is no longer considered a legitimate taxon. Explain the process of endosymbiosis and state what living organisms are likely relatives of mitochondria and plastids. Distinguish between endosymbiosis and secondary endosymbiosis. Name the five supergroups, list their key characteristics, and describe some representative taxa.
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