THE BIG GROUP the alveolates and stramenophiles Dinoflagellates

THE BIG GROUP: the alveolates and stramenophiles • • Dinoflagellates Apicomplexans Ciliates Oomycotes Diatoms Chrysophytes Phaeophyta

Dinoflagellates • Two flagella- one transverse and one longitudinal • Important to aquatic food chains. • Responsible for “red tides. ” • Some are bioluminescent. • Cellulose “plates” cover

Highlighted Species Dinoflagellate Pfiesteria piscicida • Causes “harmful algal blooms” in certain conditions. • Produces a toxin but no pigment. • Results in fish kills. May cause human illness.

Apicomplexans • Parasitic alveolate. Alveoli- membrane bound sacs. • Flagellated gametes • Mictrotubule extends from the cell and pierces the host cell.

Highlighted Species. Apicomplexans Plasmodium • Causes malaria (“bad air) • Infects Anopheles mosquitoes which then bite humans and transmit the motile life stage to the human body.

Ciliates • All have cilia, which move the cell and assist in moving food toward the cell • Cilia beat in a synchronized pattern • Contractile vacuoles that expel water from the body • Has two nuclei Didinium injesting a Paramecium

Highlighted Species. Ciliates Paramecium

Oomycotes • Similar to fungi (oomycotes= egg fungi) • They have diploid nuclei instead of haploid (as fungi have) • Decomposers • Many are parasitic and prey upon crops

Highlighted Species. Oomycotes Phytophthora infestans • Caused the Irish potato famine in the mid 1800. • Water mold with name meaning “plant destroyer” • Millions of people died as crops failed several years in a row

Chrysophytes • Group containing diatoms, yellow and golden algae and coccolithophores • Mostly photosynthetic • Coccolithophores- form calcium carbonate plates under their plasma membranes. Created White Cliffs of Dover. Can cause algal blooms which can kill fish. • Diatoms- Silica shell shaped like a pillbox. Very important primary producers that release about as much free oxygen as plants do on land.

Phaeophyta (Brown Algae) • Olive green and brown seaweeds • Sargassum- a seaweed growing in the Sargasso sea

Endosymbiotic Theory • Proposed by Lynn Margulis in 1967. • Explains similarities between prokaryotes and organelles. • Chloroplasts (and mitochondria) are the result of endocytosis of photosynthetic bacteria by an anaerobic bacteria.

Endosymbiotic Theory