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Algae- Plant- like Protists Textbook 17.4 pp. 390-394 Plant –like Protists- Algae AutotrophsPhotosynthetic- chloroplasts-supply O2 Classified by: Type of cell wall Pigments Structure Storage carbohydrates Reproduce asexually and sexually Most are unicellular; some are colonial and multicellular Euglena Euglenoids Single celled Photosynthetic One or two flagella Lack cell wall Live in freshwater Example- Euglena- can be both an autotroph and a heterotroph. B. Dinoflagellates Single-celled; found in fresh and salt water. Cellulose cell wall. Two flagella. Plankton- surface of ponds, lakes, oceans Serve as basis of aquatic food chains. Phytoplankton- photosynthetic Zooplankton- non-photosynthetic protozoans Algae blooms- population explosion due to excess nitrates. Red tides Toxins deadly to fish and humans Pfiesteria- bleeding sores in fish; neurotoxin affects humans Bioluminescent- some produce light. C. Diatoms Single-celled algae found in fresh & salt water. Glass-like cell wall of silicaMany different refractile shapes All contain chlorophyll; but other pigments Many colors of brown or yellow. Impt. Food source for marine animals. Float near the surface- oil reserves. When diatoms die; sink and fossil remainsdiatomaceous earth are mined. Uses- grinding/polishing products, filter materials, toothpaste. D. Seaweeds Large multicellular algae Not plants- No true roots,stems, or leaves. All have chlorophyll. 3 groups based on pigments/ color. Brown algae- Kelp- biggest- up to 60 m. Red algae- tropical- deepest waters; 1 type=agar. Green algae- evolutionary ancestor of plants. Single- celled- Chlamydomonas with 2 flagella Colonial- Volvox ( 100-1000s of cells moving in unison) Multicellular- filaments- Oedogonium, Spirogyra Seaweed Uses- Fungus-like Protists Textbook 17.3 pp.387-389 Fungus-like Protists A. Slime “molds” Not true molds which are fungi Decompose dead organic mater 2 types: Plasmodial Slime MoldsCellular Slime Molds 1. Plasmodial Slime Molds Plasmodium- mass of cytoplasm ,no membranes , no cell walls, many nuclei. Giant supercell ,streaming cytoplasm – amoeba like. Life Cycle Limited resources- reproductive structures- fruiting bodies (sporangia) formed. Sporangia release haploid spores. Better conditions- haploid spores fuse into diploid zygote. New plasmodium develops. 2. Cellular Slime Molds Unicellular and Multicellular stages Individual, colony, and spore stages. Asexual and Sexual reproduction. Scarce food- cells stick together Slug-like colony Trail of slime B. Water molds- Oomycota Freshwater. Decomposed dead plants,animals. Parasitic forms- skin or gills of fish. Unicellular or multicellular Sexual reproduction- egg cell Downy molds Reproduce sexually- egg cell Spores- wind blown Plant parasites Irish potato famine –mid 1800s Example of effects of clones Lack of genetic variation Water and Downy moldsDNA studies More closely related to plant-like protists (algae) Evolution Textbook 17.5 pp. 395-397 Evolution hypothesis Protists evolved from ancient prokaryotes Animals, Plants, and Fungi evolved from animal-like, plant-like, and fungus-like protists 2 main processes-explain complex eukaryotic cell. Infolding Endosymbiosis Infolding: Inward folding of cell membrane of bacterial cells Produced internal membranes of eukaryotic cells: nuclear membrane, endoplasmic reticulum, golgi apparatus. Eukaryotic Cell- separate compartments for chemical reactions. Endosymbiosis: Explains mitochondria & chloroplasts Phagocytosis of smaller bacteria into a host cell resulting in a symbiotic relationship. Mitochondria- engulfment of aerobic bacteria. Chloroplasts- engulfment of photosynthetic bacteria. EvidenceMitochondria & chloroplasts are similar to bacteria Contain DNA, RNA & ribosomes. Replicate their DNA and reproduce by binary fission. Giardia have no mitochondria.