Kingdom Protista: This system of classification is no longer used. It is now recognized that some protista are more closely related to _________________________________________________________ Protist – eukaryotes that are _____________________________________________________. Nutrition 1. 2. 3. Diverse habitats Plankton Phytoplankton – Zooplankton The _______________ and _______________ found in the protista are believed to have evolved through ____________________. LE 28-3 Plastid Dinoflagellates Secondary endosymbiosis Apicomplexans Red algae Cyanobacterium Primary endosymbiosis Stramenopiles Secondary endosymbiosis Heterotrophic eukaryote Plastid Euglenids Secondary endosymbiosis Green algae Chlorarachniophytes A tentative phylogeny of eukaryotes divides eukaryotes into many clades Excavata (Diplomonads, Parabasalids, & Euglenozoans) Diplomonads & Parabasalids 1. 2. 3. Examples: Giardia intestinalis and Trichomonas vaginalis Euglenozoans 1. 2. Examples: Kinetoplastids – Trypanosoma – Euglenids – LE 28-8 Long flagellum Eyespot Light detector Short flagellum Nucleus Euglena (LM) Contractile vacuole 5 µm Plasma membrane Chloroplast Pellicle Paramylon granule “SAR” Clade (Stramenopiles, Alveolates, & Rhizarians) Stramenopiles - Examples: Oomycetes – LE 28-14_3 Oogonium Germ tube Egg nucleus (n) Cyst Antheridial hypha with sperm nuclei (n) MEIOSIS ASEXUAL REPRODUCTION Zoospore (2n) FERTILIZATION Zygote germination Zoosporangium (2n) Zygotes (2n) SEXUAL REPRODUCTION Key Haploid (n) Diploid (2n) Alternation of Generations – alternation of multicellular haploid and diploid stages Diatoms – Golden Algae – Brown Algae – Alveolates Examples: Dinoflagellates – Apicomplexans Ciliates – FEEDING, WASTE REMOVAL, AND WATER BALANCE Paramecium, like other freshwater protists, constantly takes in water by osmosis from the hypotonic environment. Bladderlike contractile vacuoles accumulate excess water from radial canals and periodically expel it through the plasma membrane. Contractile vacuole Paramecium feeds mainly on bacteria. Rows of cilia along a funnel-shaped oral groove move food into the cell mouth, where the food is engulfed into food vacuoles by phagocytosis. Oral groove Cell mouth Thousands of cilia cover the surface of Paramecium. 50 µm Food vacuoles combine with lysosomes. As the food is digested, the vacuoles follow a looping path through the cell. Micronucleus Macronucleus Rhizarians – Examples: Forams – Cercozoans Radiolarians - The undigested contents of food vacuoles are released when the vacuoles fuse with a specialized region of the plasma membrane that functions as an anal pore. Archaeplastida - Examples: Red Algae – Green Algae – Unikonts – Amoebazoans 1. 2. Slime Molds – Plasmodial Slime Molds - Cellular slime molds Tubulinids – Gymnamoebas - Entamoebas – Opisthokonts -
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