Lecture Notes: Diversity of Protists

Overview

• Protists: Known as the "kingdom of the junk drawer" for organisms that don’t fit neatly into other kingdoms.
  • Not clearly plants, animals, or fungi.
• Composed of eukaryotic cells.

Categories of Protists

1. Plant-like (Algae)

   • Perform photosynthesis using pigments.
   2. Animal-like (Protozoans)
   • Require food intake (heterotrophic).
   • Includes free-living organisms and parasites.

2. Fungi-like (Water and Slime Molds)

   • Decompose organic material.
   • Lack typical fungal cell walls.

Algae (Plant-like Protists)

• Green Algae: Includes single-celled and multicellular organisms.

  • Spirogyra: Spiral chloroplasts.
  • Ulva: Also known as sea lettuce, used in sushi.
  • Chara: Seen in freshwater ponds.
  • Volvox: Colonial green algae.

• Red Algae: Contains red pigments.

  • Used in agar production.
  • Utilized in gel caps and sushi wraps.

• Brown Algae: Includes large seaweeds like kelp.

  • Produces algin, used in food products like ice cream for texture.

• Golden Brown Algae (Diatoms):

  • Have hard, calcified shells.
  • Used in scouring agents (e.g., toothpaste).

• Dinoflagellates:

  • Have flagella and are capable of photosynthesis.
  • Responsible for harmful algal blooms (red tides).

Protozoans (Animal-like Protists)

• Divided by locomotion:

  1. Flagella (Zooflagellates)

     • Trypanosomes: Cause diseases like sleeping sickness.
     • Giardia: Waterborne parasite causing diarrhea.
     • Trichomonas: Causes STDs.
     • Euglena: Mix of plant-like and animal-like features.

  2. Pseudopods

     • Amoebas: Some cause dysentery and rarely enter the brain.

  3. Cilia

     • Include organisms like paramecium with oral grooves for feeding.

  4. Spore Formers

     • Associated with diseases like malaria (e.g., Plasmodium).
     • Include Toxoplasma (transmitted via cat feces).
     • Cryptosporidium: Known for causing outbreaks like the one in Milwaukee.

Fungi-like Protists

• Water and Slime Molds:
  • Decompose organic matter.
  • Lack specific cell wall characteristics of true fungi.

Importance of Protists

• Disease: Some cause significant human diseases.
• Ecological Contributions:
  • Major producers of oxygen.
  • Integral part of aquatic food webs.
• Commercial Uses:
  • Ingredients in products like toothpaste and ice cream.

Laboratory Observations

• Students will observe various protists using microscopes.
• Focus on distinguishing between green, red, and brown algae.

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Key Takeaways

• Protists exhibit a wide range of characteristics and forms.
• They play crucial roles in ecosystems and human industry.
• Understanding protists help in ecology and health sectors.