THE BIG GROUP: the alveolates and stramenophiles
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Transcript of THE BIG GROUP: the alveolates and stramenophiles
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 SpeciesDinoflagellate
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