🧫 Protists

• Protist Domain

Eukarya.

• Kingdom Protista

No longer used due to paraphyly.

• Paraphyletic

Group that includes some but not all descendants of a common ancestor.

• Protist Diversity

Protists vary in body form, nutrition, and reproduction.

• Protist Relatives

More closely related to plants, animals, or fungi depending on lineage.

• Protist Complexity

More complex than prokaryotes; have organelles and diverse structures.

• Protist Metabolism

Photoautotrophic, chemoheterotrophic, mixotrophic.

• Mixotroph

Can photosynthesize and ingest organic material.

• Protist Reproduction

Asexual and sexual; life cycles vary.

• Protist Roles

Producers, consumers, decomposers in ecosystems.

• Trophic Level

Position in a food chain; protists span multiple levels.

• Protist Body Forms

Unicellular, colonial, filamentous, multicellular.

• Protist Motility

Flagella, cilia, pseudopodia, cytoplasmic streaming, metaboly.

• Protist Structures

Pellicle, cellulose plates, siliceous frustules, calcium carbonate tests.

• Protist Examples

Euglena, Paramecium, Dinoflagellates, Diatoms, Entamoeba.

• Protist Supergroups

Excavata, SAR Clade, Archaeplastida, Unikonta.

• SAR Clade

Includes Stramenopiles, Alveolates, Rhizarians.

• Unikonta

Includes Amoebozoa and Opisthokonta (animals, fungi).

• Excavata

Includes Euglena and Trypanosoma.

• Protist Pathogens

Plasmodium, Naegleria, Toxoplasma, Trypanosoma.

• Vector

Organism that transmits pathogens (e.g., mosquito, tsetse fly, kissing bug).

• VSGs

Variant surface glycoproteins used by parasites to evade immune detection.

• Infectious Disease

Caused by pathogens like protists.

• Autoimmune Disease

Immune system attacks own cells.

• Hormonal Disease

Caused by hormone imbalance.

• Idiopathic Disease

Unknown cause.

• Deficiency Disease

Caused by lack of nutrients (e.g., goiters from iodine deficiency).

- Protists & Monophyly

Protists are no longer considered a monophyletic group because they do not share a single common ancestor exclusive to them; they are paraphyletic.

- Protist vs Plant/Animal/Fungi

Protists are typically unicellular or simple multicellular, lack specialized tissues, and show diverse modes of nutrition and reproduction.

- Importance of Studying Protists

Protists play key ecological roles (e.g., producers, decomposers) and are medically significant as pathogens (e.g., Plasmodium causes malaria).

- Trophic Level

A position in a food chain; protists can be producers (e.g., phytoplankton), consumers, or decomposers.

- Protists in Food Webs

Phytoplankton are primary producers; zooplankton consume them; parasitic protists affect host populations.

- Parasitic Defense Mechanisms

Protists like Trypanosoma use VSGs to evade immune detection; Plasmodium hides in liver cells; Toxoplasma forms cysts.

- Protist Body Forms

Unicellular, colonial, filamentous, and multicellular forms exist among protists.

• Nutritional Modes

Photoautotrophs (e.g., diatoms), chemoheterotrophs (e.g., amoebas), mixotrophs (e.g., Euglena).

- Photoautotroph

Uses light energy to produce organic compounds from CO₂.

- Chemoheterotroph

Consumes organic molecules for energy and carbon.

- Mixotroph

Combines photosynthesis and heterotrophic feeding.

- Protist Motility

Includes flagella, cilia, pseudopodia, cytoplasmic streaming, and metaboly.

- Protist Structures

Includes pellicles, cellulose plates, siliceous frustules, and calcium carbonate tests.

- Ecological Roles

Protists contribute to nutrient cycling, oxygen production, and food web dynamics.

- Cellular Chemistry

Protists vary in membrane composition, metabolic enzymes, and storage molecules.

- Cellular Structures

Protists possess membrane-bound organelles, contractile vacuoles, and diverse surface structures.