Lecture Notes: Protists

Overview

• Completion of the lecture series on protists, focusing on the last two of the six supergroups of eukaryotes.
• Focus on the supergroups: Chromalveolata and Excavata.

Chromalveolata

• Large supergroup; contains photosynthetic organisms, although not all members retain this ability.
• Divided into two clades: Alveolates and Stramenopiles.

Alveolates

• Dinoflagellates:
  • Mostly marine plankton, characterized by drifting lifestyle.
  • Notable for causing red tide algal blooms (toxic) and bioluminescence.
  • Some are photosynthetic partners of corals (symbiotic relationship).
• Apicomplexans:
  • All are parasites with complex life cycles.
  • Include parasites like Plasmodium spp. which causes malaria.
• Ciliates:
  • Covered in cilia, single-celled, heterotrophic (eat bacteria).
  • Not photosynthetic.

Stramenopiles

• Distinguishing feature: hairy flagella.
• Diatoms: Photosynthetic, planktonic, unique silica shells.
• Golden Algae: Photosynthetic, form branching colonies.
• Brown Algae (Kelp/Seaweed):
  • Photosynthetic, multicellular, similar to plants through convergent evolution.
• Oomycetes:
  • Saprobes or parasites, similar to fungi.
  • Notable member: Phytophthora infestans, causing potato blight.

Excavata

• Named for their cell’s feeding groove.
• Includes several groups:

Diplomonads

• Have two non-identical haploid nuclei.
• Reduced mitochondria known as mitosomes.
• Notable member: Giardia lamblia (hiker's diarrhea).

Parabasalids

• Reduced mitochondria, presence of axostyle for attachment.
• Notable members:
  • Trichomonas vaginalis, causing trichomoniasis (STI).
  • Trichonympha, symbiotic with termites for cellulose digestion.

Euglenozoans

• Flagella used for feeding (heterotrophic and autotrophic - mixotrophs).
• Notable parasite: Trypanosoma brucei, causes African sleeping sickness.

Additional Notes

• "Protozoa" refers to single-celled heterotrophic protists, though not evolutionarily significant.
• Completes the chapter on protists, marking the end of exam number one material.