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Tuesday, December 21, 2010
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
Ciliates
l Ciliates- use cilia to move and feed.
l Coordinated by submembrane system of microtubules (widespread or clumped)
l Complex unicellular organisms found in fresh water
l Two types of nuclei:
l large macronucleus which controls everyday functions. Has 50 or more copies of genome. Splits during binary fission
l Small micronuclei are exchanged in a process called conjugation. Provide for genetic recombination.
Life Cycle of Plasmodium, protest that causes Malaria
l Apicomplexans- animal parasites, complex life cycles (sexual and asexual stages and several host species)
l Spread by tiny infectious cells called sporozoites
l Cause malaria
Monday, December 13, 2010
What is a Protist?
l Kingdom Protista has been split into as many as 20 Kingdoms
l Most protists are unicellular.
l Most protists are aerobic. Some are photoautotrophs (contain chloroplast), heterotrophs (absorbing organic molecules or ingesting larger food molecules), or mixotrophs (combine photosynthesis and heterotrophic nutrition)
l Can divide protists into three categories: ingestive/protozoa (animal-like), absorptive (fungus like), and photosynthetic/algae (plantlike)
l Most protists are motile, having cilia or flagella at some point. These structures are extensions of the cytoplasm.
Protista
• Alveolata
• Cercozoa
• Amoeba
• Euglenozoa
• Diplomonadida
• Parabasala
• Stramenopila
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