Lecture on Protists

Overview of Protists

• Kingdom Division: Protists are eukaryotes that couldn't be classified as plants, animals, or fungi.
• Characteristics:
  • Eukaryotic cells with a nucleus (some with more than one).
  • Prefer moist environments.
  • Can be unicellular or multicellular.
  • Nutritional modes include autotrophy (photosynthesis), heterotrophy (consumption of organisms), or both.
  • Some are motile, others are not.

Classification of Protists

1. Animal-like Protists (Protozoans)

   • Characteristics:
     • Unicellular and heterotrophic.
     • Four movement groups: pseudopods, cilia, flagella, and non-motile.
   • Examples:
     • Sarcodines (Amoebas): Use pseudopods for movement and feeding.
     • Ciliates (e.g., Paramecium): Move using hair-like cilia; have macronucleus and micronucleus.
     • Zooflagellates: Move with long flagella.
     • Sporozoans (e.g., Plasmodium): Parasitic and rely on hosts for movement and nutrition.

2. Plant-like Protists (Algae)

   • Characteristics:
     • Autotrophic; perform photosynthesis.
     • Range from unicellular to large multicellular forms like giant kelp.
     • Possess different pigments.
   • Examples:
     • Diatoms: Have silica shells.
     • Euglena: Can be autotrophic or heterotrophic; use flagella for movement.

3. Fungus-like Protists

   • Characteristics:
     • Heterotrophic decomposers.
     • Have cell walls with cellulose.
     • Capable of spore reproduction.
   • Examples: Water molds, slime molds, downy mildew.

Diseases Caused by Protists

• Chagas Disease: Caused by Trypanosoma; transmitted by the kissing bug.
• Sleeping Sickness: Caused by Trypanosoma via the tsetse fly.
• Giardiasis: Caused by Giardia; spreads via contaminated food and water.
• Malaria: Caused by Plasmodium, transmitted by mosquitoes.
• Amoebic Dysentery: Causes gastrointestinal symptoms; transmitted via contaminated water and food.

Prevention and Treatment

• Common prevention methods include hand washing, avoiding face touching, using insect repellent, and boiling potentially contaminated water.
• Mosquito Nets: Effective in preventing malaria.
• Medicines: Some antibiotics and antiparasitic drugs are effective, but development is challenging due to similarities to human cells.

These notes summarize the key points from the lecture on protists, covering their classification, characteristics, and implications for human health.