Tuesday, December 14, 2010

Stramenopila and its Types

l      Includes heterotrophs and various groups of photosynthetic protists

l      Major characteristic: hairlike projections on the flagella
l      Only reproductive cells are flagellated
l      One smooth and one “hairy” flagellum
l      Oomycota, Bacillariophyta (diatoms), chrysophyta (golden algae), Phaephyta (brown algae)
l      Oomycota- water molds, white rusts, downy mildews = heterotrophic stramenopiles  
l      Resemble fungi in appearance but not closely related
l      Cell walls made of cellulose
l      Predominant diploid stage
l      Biflagellated cells
l      Filamentous body plans to absorb nutrients
l      Large egg cell and smaller sperm
l      Water molds=important decomposers in aquatic ecosystems

l      Bacillariophyta- diatoms- unicellular marine and freshwater plankton
l      Boxlike silica walls, glassy
l      Asexual reproduction however eggs and sperm produced also
l      Food- glucose polymer, laminarin

l      Chrysophyta- golden algae- yellow and brown carotene and xanthophyll accessory pigments
l      Unicellular, biflagellated
l      Marine and freshwater plankton
l      Some are mixotrophic
l      When population becomes too high, many species form long-lasting cysts 

l      Phaeophyta- brown algae- largest and most complex algae
l      Color due to accessory pigments in their plastids

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