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“Plant-Like” Protists:. Unicellular Algae. Unicellular Algae. Chlorophyll and accessory pigments allow algae to harvest and use energy from sunlight. Both give algae a wide range of colors. Phylum Euglenophyta - Euglena. “Plant-like” protists that have two flagella but no cell wall
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“Plant-Like” Protists: Unicellular Algae
Unicellular Algae • Chlorophyll and accessory pigments allow algae to harvest and use energy from sunlight. • Both give algae a wide range of colors
Phylum Euglenophyta - Euglena • “Plant-like” protists that have two flagella but no cell wall • Red eye-spot – helps organism find sunlight to power photosynthesis • Phototrophic autotroph or heterotroph (absorb nutrients in decayed organic material) • Pellicle – cell membrane • Reproduce asexually by binary fission
Euglena Anatomy Chloroplast Carbohydrate storage bodies Gullet Pellicle Contractile vacuole Nucleus Flagella Eyespot
Phylum Pyrrophyta - Dinoflagellates • Half are photosynthetic, half are heterotrophs • Two flagellas • Reproduce asexually by binary fission • Some luminescent/give off light • Only eukaryote with no histones to help store DNA
Phylum Chrysophyta • Mostly solitary • Yellow-green and golden-brown algae • Gold-colored chloroplasts • Cell walls contain pectin rather than cellulose; others can have both pectin and cellulose • Reproduce asexually and sexually • Store oil, not starch
Phylum Bacillariophyta – Diatoms • Most abundant organisms on Earth • Thin, silicon cell walls
Ecology of Unicellular Algae • Helpful: • Phytoplankton – diatoms and dinoflagellates • 70% of photosynthesis occurs in ocean • Symbiosis – corals and dinoflagellates – Tridacha gigas (clam) and dinoflagellates • In both cases, algae provide food to the animal
Ecology of Unicellular Algae • Harmful: • Algae “blooms” – dangerous toxin produced by algae – shellfish eat the algae and eat the toxin = people can’t eat it • Dinoflagellate Gonyaulx – red tide
“Fungus-like” Protists • Heterotrophs that absorb nutrients from dead or decaying matter. Unlike true fungi, “fungus-like” protists have centrioles and lack chitin in cell walls • Recyclers of dead organisms
Slime Molds • Play key roles in recycling organic material • 3 Phyla of slime molds • Phylum Acrasiomycota • Phylum Myxomycota • Phylum Oomycota
Phylum Acrasiomycota • Cellular slime molds • Begin life as amoeba-like cells • When food begins to run out, then form colonies and produce a fruiting body which produces spores • Spores “hatch” into amoeba-like cells
Phylum Myxomycota • Acellular slime molds • Begin life as amoeba-like cell, called plasmodia, that contain thousands of nuclei but only one cell membrane • Plasmodia may reach several meters in diameter • Form fruiting bodies • Produce haploid spores which germinate into flagellate cells which fuse to produce the diploid “amoeba”
Phylum Oomycota • Water molds • Thrive on dead or decaying organic matter in water and are plant parasites on land • Hyphae – thin filaments • A water mold caused the potato famine in Ireland in 1840s