Chapter 28 / Protists. I. Introduction A. Eukaryotes 1. 1 st eukaryotic organisms 2. most are unicellular 3. considered simple. Part I: Protozoans

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1 Randa, Bio Chapter 28 / Protists I. Introduction A. Eukaryotes 1. 1 st eukaryotic organisms 2. most are unicellular 3. considered simple B. Protist diversity (ecological grouping) 1. comprised of: a. protozoans--heterotrophs free-living or symbiotic b. slime molds } saprotrophs c. water molds d. algae autotrophs 2. formerly, lumped in single, kingdom [but, paraphyletic] --now up to 20 different kingdoms! C. Protist life-styles 1. all require moist/wet environments 2. many are aquatic plankton 3. many are motile cilia, flagella, amoeboid motion, drift in currents 4. reproduce asexually (most also sexually) Part I: Protozoans II. Protozoans --heterotrophic, similar to animals A. Clade Amoebozoa amoebae with lobe-shaped pseudopodia 1. unicellular (Rhizopods: Gymnamoebas and Entamoebas) or aggregates of cells (the slime molds) 2. locomotion by pseudopodia also means to engulf food phagocytosis 3. internal structure contractile vacuole, food vacuole, lysosomes, nucleus 4. some free-living, some parasitic

2 Randa, Bio B. Clades Cercozoa and Radiolaria amoebae w/ thread-like pseudopodia 1. Actinopoda a. have skeletons of silica: single fused piece in radiolarians, unfused plates (maybe chitinous) in heliozoans b. some marine (radiolarians), some live in fresh water (heliozoans) c. have very thin pseudopodia, called axopodia 2. Foraminifera the forams (clade Cercozoa) a. multichambered, porous shells (tests) b. marine organisms c. locomotion: pseudopodia extend through pores; also used for feeding and building shell d. >90% of described forams are fossils e. Many forams form symbioses with algae C. Clade Alveolata: ciliates, apicomplexans, dinoflagellates --have alveoli, small membrane-bound cavities, under the cell surface --may help stabilize the cell surface and regulate water and ion content 1. Ciliophora the ciliates a. unicellular, most in freshwater b. cilia c. structures: i. 2 nuclei: micronucleus and macronucleus ii. oral groove iii. food vacuole iv. contractile vacuole v. trichocysts to capture prey d. genetic recombination via conjugation 2. Apicomplexa the apicomplexans a. all parasitic b. locomotion flexing c. no contractile vacuoles d. produces spores in 1st host, used to infect 2nd host Plasmodium, causes malaria sexual reproduction occurs in Anopheles mosquito host a. mosquito ingests infected blood b. reproduction in mosquito salivary glands c. transmits to human through bite d. liver e. red blood cells

3 Randa, Bio Dinoflagellates unicellular or colonial 2 flagella cellulose shells many autotrophic some cause red tides D. Clade Euglenozoa 1. Euglenids unicellular 1 flagella some heterotrophs, some autotrophs Euglena: chloroplasts, eye spot 2. Kinetoplastids have a single large mitochondrion and a unique organelle, the kinetoplast houses extranuclear DNA are symbionts Trypanosoma --causes African Sleeping Sickness E. Clade Parabasla --lack mitochondria E.g. Trichonympha, Trichomonas vaginalis: F. Clade Diplomonadida multiple flagella, two separate nuclei, simple cytoskeleton, no mitochondria or plastids Giardia lamblia Part II: Algae Algal characteristics: 1. can have chlorophyll a and b, c, or d 2. possess accessory pigments e.g., carotenoids, phycobillins 3. size range: microscopic to macroscopic Dissimilarities to plants 1. lack cuticle, true roots, stems, and leaves 2. lack true gametangia--reproductive organ surrounded by extra layer of nonreproductive cells

4 Randa, Bio III. Algal Taxonomy and Diversity A. Clade Alveolata Dinoflagellates 1. unicellular or colonial 2. 2 flagella 3. cellulose shells 4. many autotrophic: may be endosymbionts with coral and mollusks 5. some cause red tides--release paralytic toxins B. Clade Stramenopila Bacillariophytes / Diatoms 1. unicellular or colonial 2. 2 part silica shell 3. most autotrophic 4. yield diatomaceous earth 5. plankton--important in Arctic/Antarctic food chain C. Clade Euglenozoa Clade Euglenophyta 1. unicellular; freshwater 2. 1 exposed flagellum, other in reservoir 3. some heterotrophs, some autotrophs 4. Euglena: chloroplasts, eye spot (stigma), paramylon granules 5. has flexible pellicle 6. increase with eutrophication D. Clade Chlorophyta--the green algae 1. very diverse: include unicellular, colonial, multicellular forms 2. some characteristics similar to plants e.g., photosynthetic pigments: chlorophyll a and b and carotenoids cellulose in cell walls similar mitotic division (some) 3. flagellated cells at some point in life 4. aquatic or terrestrial 5. sexual reproduction: isogamous, anisogamous, oogamous E. Clade Strameopila Clade Phaeophyta--the brown algae 1. marine; mainly cooler waters 2. chlorophyll a and c and carotenoids 3. large multicellular (kelp) have specialized body parts: blade, stipe, holdfast, float F. Clade Stramenopila, Clade Chrysophyta--golden algae 1. colonial (some unicellular), 2 flagella per cell 2. important component of freshwater plankton 3. chlorophyll a and c and carotenoids and xanthophyll

5 Randa, Bio G. Clade Rhodophyta--the red algae 1. most marine (warmer waters) 2. multicellular, no motile cells 3. contain phycoerythrin and phycocyanin; chlorophyll a and d 4. used to make agar, carrageenan Part III: The Fungal-like Protists IV. Slime and Water Molds --similar to fungi in lifestyle (saprophytic) and appearance --dissimilar to fungi by possession of: flagellated cells centrioles cellulose in cell wall A. Clade Amoebozoa-Clade Myxogastrida plasmodium: can creep like amoeba Reproduction: sporangia haploid spores swarm cell or myxamoeba zygote plasmodium B. Clade Amoebozoa-Clade Dictylostelida feeding stage: single, haploid amoeboid cell can aggregate pseudoplasmodium (slug) spores C. Clade Stramenopila Clade Oomycota--water molds produce flagellated cells at 1 point in life cycle like fungi, form mycelium; cell walls may contain chitin Reproduction: asexual (favorable conditions) sexual--oospores (less favorable conditions) Some are important pathogens.

Protists. There are NO typical protists. Protist General Characteristics - usually single cell - eukaryotic - paraphyletic group

Protists. There are NO typical protists. Protist General Characteristics - usually single cell - eukaryotic - paraphyletic group There are NO typical protists. Protist General Characteristics - usually single cell - eukaryotic - paraphyletic group Traditional Classification There are three divisions of the Kingdom Protista: Protozoa,