PROTISTA

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PROTISTA

• Chapter 21

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• A. The Basal Eukaryotes
• Includes several distantly related groups
  believed to be the earliest unicellular
  eukaryotes to diverge.
• 1. Basal Eukaryotes Lacking Mitochondria
• Ancestors of these organisms may have diverged
  before the endosymbiotic event that gave rise to
  mitochondria.

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• Parabasalia - flagellated organisms found only in
  association with animals.
• Trichomonas vaginalis causes the STD
  trichomoniasis.

Trichonympha live in termites contain bacteria
that digest cellulose.

• Diplomonadida - flagellated organisms found in
  stagnant fresh water or in intestines.

Giardia lamblia causes hikers diarrhea.
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• 2. Basal Eukaryotes With Mitochondria
• Amoebae - aquatic organisms that use pseudopodia
  to move to feed.
• Amoeba proteus

• Acellular slime molds - heterotrophic organisms
  that exist as an amoeboid mass called a
  plasmodium.
• Physarum

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• Cellular slime molds - heterotrophic organisms
  that exist as single cells.
• When food is lacking, cells aggregate to form a
  multicellular slug.

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• Euglenida - organisms that possess an anterior
  chamber from which one or two flagella emerge.

Euglena is a pond dwelling organism has both
plant animal characteristics.
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• Kinetoplastida (trypanosomes) - flagellated
  organisms have a single, large mitochondrion
  containing a kinetoplast (houses extracellular
  DNA).

Trypanosoma brucei causes African sleeping
sickness transmitted to humans by bite of tsetse
fly.
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• B. The Alveolates
• Includes protists that have alveoli beneath the
  cell membrane.
• 1. Dinoflagellates - organisms possessing a pair
  of flagella that cause the cell to spin as it
  swims major components of phytoplankton.

Gonyaulax blooms cause red tides. Pfiesteria
piscicida has 24 stage life cycle.
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• 2. Ampicomplexans - obligate parasites of
  animals all possess an apical complex have
  complex life cycles.

Plasmodium causes malaria transmitted to humans
by mosquitoes.
Toxoplasma gondii causes toxoplasmosis pregnant
woman can become infected via cat feces pass
disease to fetus.
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• 3. Ciliates - organisms that move by means of
  cilia.

Paramecium
Didinium
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• C. The Stramenopiles
• Includes protists that have unique flagella
  laminarin photosynthetic stramenopiles have
  pigments not found in plants.
• 1. Water molds (oomycetes) - absorb nutrients
  from their surroundings.

Plasmopara viticola causes downy mildew of
grapes. Phytophthora infestans causes late
blight of potatoes.
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• 2. Diatoms - organisms that have two-part silica
  walls called frustules major components of
  phytoplankton.

Abrasiveness of frustules makes diatoms useful
ingredients in polishes.
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• 3. Brown algae - large, multicellular seaweeds
  brown color is due to the photosynthetic pigment
  fucoxanthin.
• Giant kelp

4. Golden algae - most are unicellular golden
color is due to carotene xanthophyll
photosynthetic pigments. When light or nutrient
supplies dwindle, many will consume bacteria or
diatoms.
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• D. The Red Algae
• Primarily multicellular have photosynthetic
  pigments called phycobilins.

• Useful red algal products include
• agar - used as a culture medium for microbes, and
  to thicken ice cream yogurt.
• carageenan - used to stabilize paints, cosmetics
  creamy foods.

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• E. The Green Algae
• Includes unicellular, multicellular colonial
  autotrophs that resemble plants.
• Plant-like characteristics
• use chlorophyll a b
• store starch
• have cell walls containing cellulose
• most exhibit alternation of generations

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Life cycle of the sea lettuce, Ulva
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• Green algae differ from plants
• most have pyrenoids (regions in chloroplasts that
  store starch)
• lack true stems, roots leaves

Spirogyra - multicellular filaments containing
spiral- shaped chloroplasts.
Volvox - colonial organism consisting of 500 to
600,000 biflagellate cells.