Protists Chapter 35 Copyright © McGraw-Hill Companies Permission required for reproduction or display Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Endosymbiosis Theory of endosymbiosis proposes mitochondria originated as symbiotic, aerobic eubacteria. Each mitochondrian still has its own genome in a circular, closed molecule of DNA. Divide by simple fission. Directed by nuclear genes. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Artificial group of convenience. Single-celled organisms. Classifying Protists Protists are the most diverse of the four kingdoms in the domain Eukarya. Artificial group of convenience. Single-celled organisms. Little consensus about protist classification. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

General Biology of the Protists Cell Surface - Possess varied array of cell surfaces. Locomotor Organelles flagellular rotation pseudopodial movement Cilia (short hairs covering the surface) Cyst Formation - Dormant form of a cell with resistant outer covering in which metabolism is essentially shut down. Nutrition Employ all forms but chemoautotrophic. -Phototrophs -Heterotrophs --Phagotrophs - Visible food particles. --Osmotrophs - Food in soluble form. Reproduction Typically reproduce asexually. Sexual reproduction in times of stress. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Five Groups of Protists Group according to shared characteristics: Presence/Absence of cilia or flagella. Presence and kinds of pigments. Type of Mitosis. Kinds of cristae in mitochondria. Molecular genetics of ribosomal S subunit. Inclusions Overall body form. Armor Modes of nutrition and movement. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

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Heterotrophs with No Permanent Locomotion Largest of the five general groups. Three Principal Phyla Rhizopoda: Amoebas Move by pseudopods. Actinopoda: Radiolarians Secrete glassy exoskeletons. Foraminifera: Forams Pore-studded shells Cytoplasmic projections (podia) Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Photosynthetic Protists Pyrrhophyta: Dinoflagellates Mostly unicellular photosynthetic organisms. Distinctive flagella, protective coats, and biochemistry. Zooxanthellae Grow as symbionts within other cells lacking characteristic cellulose plates and flagella. Produce primarily by asexual cell division. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Dinoflagellates Copyright © McGraw-Hill Companies Permission required for reproduction or display Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Photosynthetic Protists Euglenophyta: Euglenoids Most are freshwater. About one-third are autotrophic. Pellicle lies within membrane. Stigma - Light sensitive organ that aids in orienting towards light. Euglena Two flagella attached to reservoir. Contain numerous chloroplasts. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

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Photosynthetic Protists Chrysophyta: Diatoms and Golden Algae Diatoms - Photosynthetic,unicellular organisms with double shells of opaline silica. Divided into radial and bilateral symmetry. Golden Algae - Named for yellow and brown carotenoid and xanthophyll accessory pigments in chloroplasts. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Photosynthetic Protists Rhodophyta: Red Algae Colors results from phycobilin pigment, phycoerythrin. Great majority of species occur in sea. Interwoven filaments of cells. Phaeophyta: Brown Algae Multicellular protists, almost exclusively marine. Kelp forests. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Photosynthetic Protists Chlorophyta: Green Algae Extensive fossil record dating back 900 million years. Mostly aquatic Chlamydomonas is well-known genus. Probably represents primitive state. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

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Heterotrophs with Flagella Zoomastigophora: Zoomastigotes Unicellular, heterotrophic organisms highly variable in form. Each has at least one flagellum. Includes genera Trypanosoma (African Sleeping Sickness) and Crithidia, pathogens of human and domestic animals. Giardia lamblia - Hiker’s Diarrhea. Lives in upper intestine of host. Spread by infected fecal matter. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Heterotrophs with Flagella Ciliophora: Ciliates Most members have large numbers of cilia. Usually arranged in longitudinal rows or in spirals around the body. Micronuclei (mutligene chromosomes) or macronuclei (multiple copies of a certain gene). Form vacuoles for ingesting food and regulating water balance. Usually reproduce via transverse fission. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

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Nonmotile Spore-Formers Apiocomplexa: Sporozoans Nonmotile, spore-forming animal parasites. Complex life cycles that involve both asexual and sexual phases. Malaria is caused by infection by sporozoan Plasmodium. Three different stages of the Plasmodium life cycle each produce different antigens, and are sensitive to different antibodies. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

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Heterotrophs With Restricted Mobility Oomycota Comprise water molds, white rusts, and downy mildews. All are parasites or saprobes. Life cycles characterized by gametic meiosis and a diploid phase. Motile spores, zoospores, bear two unequal flagella. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

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Heterotrophs With Restricted Mobility Acrasiomycota: Cellular Slime Molds Individual organisms behave as separate amobeas, moving through soil or other substrate and ingesting bacteria. Individual organisms aggregate and form moving mass “slug”, that eventually transforms into a spore-containing mass sorocarp. Develops stalk and releases spores. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

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Heterotrophs With Restricted Mobility Myxomycota: Plasmodial Slime Molds Stream along as a non-walled, multinucleate mass of cytoplasm, plasmodium. Produces sporangium during times of resource shortage. Forms spores that quickly undergo meiosis. Multiple nuclei in each spore disintegrate, leaving each spore with a single haploid nucleus. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Raven - Johnson - Biology: 6th Ed Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Copyright © McGraw-Hill Companies Permission required for reproduction or display Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies