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Lecture Notes 4.21

Lecture Notes 4.21 - PROTISTS unicellular eukaryotes that...

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4/21/10 PROTISTS unicellular eukaryotes that lack cell walls tremendous phylogenetic diversity; represent much of the diversity found in Eukarya Diplomonads two nuclei of equal size contain mitosomes lacking citric acid cycle and electron transport Giardia intestinalis – one of most common waterborne diarrheal diseases in USA Parabasalids Basal body gives support to Golgi complex Contain hydrogenosomesfor anaerobic metabolism Parasites living in urogenital tract of vertebrates and invertibrates o Trichomonas vaginalis - sexually transmitted diseaseof humans Unique genomes, o Most parabasilid genomes lack introns o T. vaginalis genome huge for parasite (160 mbp); contains nearly 60,000 genes (2x human genome) Euglenozoans Diverse assemblage of flagellated eukaryotes w/ crystalline rod in flagella (whose function not yet known) Some parasitic, others free-living phototrophs or chemoorganotrophs Include kinetoplasts and euglenids Kinetoplasts Named for kinetoplast; mass of DNA in single large mitochondrian Live primarily in aquatic habitats and feed on bacteria Some parasites of animals o Trypanosoma : small (20 uM) crescent-shaped cells w/single flagellum that infect humans o Trypanosoma brucei – African sleeping sickness – chronic and usually fatal Grows in bloodstream and invades CNS Spread by bite of tsetse fly; grows in intestinal tract of fly and invades salivary glands and mouthparts Euglenids Nonpathogenic and phototrophic Can lose chloroplasts in dark and feed on bacteria by 1
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phagocytosos Alveolates (al vee o lets) Presence of al ve oli (al vee uh lahy)– little cavaties under the cytoplasmic membrane (for water balance?) Three phylogenetically distinct but closely related groups o Ciliates o Dinoflagellates o Apicomplexans (āp'ĭ-k ə m- plěk 's ə n) Ciliates - e.g. - Paramecium Use cilia for motility and for ingestion of food (particulate material, bacterial cells) o ingestion into food vacuole by phagocytosis Micronucleus (sexual reproduction) and macronucleus (maintenance of basic cellular functions) Many species host endosymbionts that reside in cytoplasm or in the macronucleus o e.g . - commensal ciliates of termite hindgut harbor methanogenic Archaea o Can themselves be symbiotic as rumen protist Some species animal parasites: Balantidium coli – intestinal parasite of domestic animals that can cause dysentery-like symptoms in humans Dinoflagellates Common and diverse marine and freshwater phototrophs Flagella encircling cells give spinning motion (dinos – Greek for whirling) Some free living while others symbionts of choral reefs Several species of Gonyaulax bioluminescent – luminescence stimulated by shear forces luminescent waves or ship’s wakes Red tides – caused by toxic strains of Gonyaulax (and other Dinoflagellates) o Gonyaulax
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Lecture Notes 4.21 - PROTISTS unicellular eukaryotes that...

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