Transcript Protists
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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.
Phylogeny
• • • • • • • • • 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
Ciliate Life Cycle
Plasmodium Life Cycle
The Life Cycle of a Water Mold
Life Cycle of Multicellular Algae
(Alternation of Generation)
Life Cycle of Plasmodial Slime Mold
Life Cycle of Cellular Slime Mold
Life Cycle of Unicellular Chlorophyte
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