“Plant-Like” Protists: 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 Gullet Chloroplast Nucleus EyespotFlagella Carbohydrate storage bodies Pellicle Contractile vacuole

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