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Starter Question. What is this? Why is it important? Why is this today’s question?. Protists. By Brian Kato, Adam Resnick, and Yukako Kawakatsu. Introduction. Protists are a diverse group of eukaryotes that are not animals, plants or fungi.
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Starter Question • What is this? • Why is it important? • Why is this today’s question?
Protists By Brian Kato, Adam Resnick, and Yukako Kawakatsu
Introduction • Protists are a diverse group of eukaryotes that are not animals, plants or fungi. • They can be unicellular or multicellular, but do not have any specialized tissues. • It is hard to come up with a specific definition of a protists owing to their diversity.
Endosymbiosis • Endosymbiosis is a theory which explains the origins of plastids in eukaryotes. • It states that chloroplasts and mitochondria evolved from small bacteria engulfed by larger bacteria. • The small bacteria remained alive within the large ones, and they developed a symbiotic relationship.
Secondary Endosymbiosis • A larger organism engulfs a smaller one which has already undergone endosymbiosis. • This explains the diversity of plastids which are found in protists. • It is more difficult to determine which plastids were acquired through secondary endosymbiosis in organisms which underwent this process in the distant past.
Protozoa • Similarities to Animals:・Mobility, digestion, ingestion Algae • Similarities to plants:・Chloroplasts (produce own food), thallus (parts that correlate to plant structure) • Differences:・Lack leaves, roots, flowers, and other organ structures. Fungus-like • Similarities to fungus: • Reproduce by spores • Have hyphae (branch-like structure used to absorb nutrients) • Difference: • Use different materials in their cell walls-protists use cellulose, fungi use chitin. • They can behave as amoebas at times, while fungi grow as a single stationary unit.
Diplomonads • Two equal-sized nuclei • Multiple flagella • Ex: Giardia Parabasalids • Undulating membrane Similarities: • Modified mitochondria • Lack plastids • Most found in anaerobic environments
Euglenozoans • Predatory heterotrophs, photosynthetic autotrophs, and pathogenic parasites • Spiral or crystalline rod inside flagella • Kinetoplastids: have kinetoplast (DNA in mitochondria) • ex: Trypanosomes-sleeping sickness (“bait-and-switch”defense) • Euglenids: have paramylon as storage molecule. Switch between heterotrophs/ autotrophs according to availability of nutrients and sunlight(eyespot).
Alveolates • Alveoli beneath plasma membrane • Dinoflagellates: armor of cellulose plates • Apicomplexans: apical complex of organelles • Ciliates: cilia used in movement and feeding; macro and micronuclei.
Stramenopiles • Hairy and smooth flagella • Oomycetes: hyphae that absorb nutrients • Diatoms: glassy, two-part wall • Golden algae: flagella attached near one end of cell • Brown algae: all multicellular, some with alternation of generations
Cercozoans and Radiolarians • Amoebas with threadlike pseudopodia • Forams: porous shell • Radiolarians: pseudopodia radiating from central body
Amoebozoans • Amoebas with lobe-shaped pseudopodia • Gymnamoebas: soil-dwelling, freshwater, or marine • Entamoebas: parasites • Plasmodial slime molds: multinucleate plasmodium; fruiting bodies that function in sexual reproduction. • Cellular slime molds: multicellular aggregate that forms asexual fruiting bodies.
Red Algae • Phycoerythrin (accessory pigment) • No flagellated stages
Chlorophya (green algae) • Plant-type chloroplasts
Life Cycle of Multicellular Algae (Alternation of Generation)
Biological Niche • Parasites (ex: malaria, sleeping sickness, dysentery) • Dinoflagellates • Red tide • Mutualistic symbionts of coral polyps and the giant clam • Water molds (oomycetes) • Potato late blight • Diatoms • Diatomaceous earth mined as filtering medium • Nanotechnology-microscopic devices • Algae • Food (seaweed, soups, used to thicken pudding, ice cream, salad dressing) • Forests house marine creatures • Watermelon snow • Live symbiotically w/in other eukaryotes-contribute part of their photosynthetic output to food supply of hosts (lichens)
Reference • http://www.biology.ualberta.ca/courses.hp/zool250/Clades/clade01-Protista.htm • http://www.biology.ualberta.ca/courses.hp/zool250/Clades/CladePics/Giardia.jpg • http://www.wwdd2.net/trichomonas.bmp • http://courses.bio.psu.edu/fall2005/biol110/tutorials/tutorial27.htm • http://staff.tuhsd.k12.az.us/tcochran/BioImages/ciliate.jpg • http://www.vialattea.net/spaw/Image/biologia/Paramecium.jpg • http://microscope.mbl.edu/baypaul/microscope/taxonomy/Stramenopiles/hairflag.jpg • http://daviddarling.info/images/diatoms.jpg • http://www.laups.org/gallery2/d/934-1/perch-in-kelp-forest.jpg • http://www.spectrosciences.com/IMG/jpg/formaminifere.jpg • www.sanvalero.net/.../foram%201.JPG • http://www.bms.ed.ac.uk/research/others/smaciver/amoeba.htm • http://www.nsf.gov/od/lpa/news/03/images/amoeba_spore_tower.jpg • http://www.ucmp.berkeley.edu/protista/reds/porphyra.gif • http://www.apocalypse.org/pub/u/jen/red-algae.jpg • http://www.fathom.com/feature/122409/3329_greenAlgae_lg.jpg • http://hiperdrt.hu/sushi/kep/sushi-n-21.jpg