PROTISTS

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PROTISTS
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Protists

• Protists Unicellular eukaryotic organisms.
• Over 115,000 species
• Eukaryotic cells - contain membrane-bound
  organelles (particularly mitichondria
  chloroplasts)
• Protists eukaryotes probably evolved from a
  large eukaryotic cell ingesting a photosynthetic
  and oxygen metabolizing bacteria
• Known as endosymbiotic theory
• Two major classes of protists
• Animal-like protists
• Plant-like protists

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Animal-like Protists

• Phylum Ciliophora (Cilia bearing protists)
• Aka "ciliates"
• Have cilia (short hairlike structures) on their
  plasma membranes
• Cilia rapidly beat and provide propulsion for the
  protist.
• Over 7000 species in this phylum.
• Example is paramecium.

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Paramecium

• Large organisms 305 micrometers long
• Important features
• Have 2 nuclei
• Macronucleus (large)
• Micronucleus (smaller)
• Feed by forcing H2O into Gullet forming food
  vacuoles
• Excrete wastes through anal pore
• Excrete excess water through use of contractile
  vacuoles
• Move by coordinated movement of hair-like cilia.

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More Paramecium
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Phylum Sporozoa

• Usually parasitic in nature
• Example is Plasmodia which causes malaria.
• One of the most deadly diseases to man
• Malaria is transmitted by the Anopheles mosquito.

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Lifecycle of Plasmodia
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Phylum SarcodinaProtists with false feet

• Use extensions of cytoplasm to move and feed.
• Extensions are called pseudopods (false feet)
• Movement is by extending pseudopod, then the
  remainder of cytoplasm flows into extension.
• Feeding is done by extending 2 pseudopods around
  object and engulfing object, forming a food
  vacuole
• Examples are amoebas (amebas)

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Amoebas
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More amoebas
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Plant-like Protists

• 5 phyla of plant-like protists
• Are usually photosynthetic, and also
  heterotrophic.
• All are unicellular, most are motile
• Example Phylum Euglenophyta

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Phylum Euglenophyta

• Example is euglena.
• Has a flagellum, is motile
• Is both heterotrophic autotrophic
• Contains chloroplasts is photosynthetic.
• Can become heterotrophic in low-light conditions

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Euglena
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Dinoflagellates

• Have 2 flagella for motility
• Often have a cellulose covering

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Diatoms

• Most abundant form of marine algae.
• Form elaborate silicon (glass) shells to protect
  themselves
• Shell is porous to allow materials in/out of the
  cell.

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Multicellular / Other Algae

• Are not generally true multicellular organisms,
  but rather "colonies"
• Show beginnings of specialized functions /
  tissues
• 3 types
• Green algae
• Red Algae
• Brown algae

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Green algae (Chlorophyta)

• Green algae (Chlorophyta)
• Contain chlorophyl a b
• Most frequently found in fresh water
• Often colonial

Volvox a green colonial algae
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Red Algae (Rhodophyta)

• Red Algae (Rhodophyta)
• Found in salt/brackish water
• Have additional pigments which give them a
  reddish color.
• In uncontrolled blooms, these organisms can cause
  serious ecological damage

Red algeal bloom
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Brown Algae (Rhodophyta)

• Brown Algae (Rhodophyta)
• Most Plant-like of all algae.
• Include kelps
• Can grow to huge sizes (100')
• Most primitive plant like organism to show
  alternation of generations.

Giant Kelp Forest
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Fungus like Protists

• Fungus like Protists
• Act as decomposers
• Often have a slimy appearance/texture, hence
  their name.
• 3 types
• Plasmodial slime molds
• Cellular slime molds
• Water molds

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Plasmodial Slime Molds

• Plasmodial Slime Molds
• Can grow very large, however, is still a single
  cell (with many nuclei)
• Feeding stage is called a plasmodium.
• Forms fruiting bodies under stress.

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Cellular Slime Molds

• Cellular Slime Molds
• Exists a majority of its life cycle as an amoeba
• In  times of stress these amoebas unite to form a
  Pseudoplasmodium, which crawls to another
  location (slug form), and forms a fruiting body

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Water molds

• Water molds
• Completely aquatic
• Often decomposers
• Sometimes parasitic

Water mold attacking a fish