9. Protista Lesson

Kingdom Proti O

Success Criteria

  • Describe basic characteristics of protists.

  • Identify differences between animal-like, plant-like, and fungi-like protists.

  • Explain the impact of protists on the environment and society.

Cell Types

  • Prokaryotes

  • Eukaryotes

    • Kingdoms:

      • Animalia

      • Plantae

      • Fungi

      • Protista

What Are Protists?

  • Eukaryotic microbes (first cells with a nucleus).

  • Ecological Diversity: 65K – 200K species.

  • Examples include amoebas, paramecium, diatoms.

  • Miscellaneous group; organisms not fitting into other kingdoms.

Characteristics of Protists

  • Origins: appeared about 1.5 billion years ago.

  • All are eukaryotic (unicellular or multicellular).

  • Most are unicellular, some multicellular.

  • Reproduction: asexually (binary fission) and sexually (conjugation).

  • Habitat: mainly in water (fresh/salt), damp areas, or animal fluids.

  • Ancestors of fungi, plants, and animals.

Protist Classification

  • Based on how they obtain nutrition and how they move.

Methods of Obtaining Energy

  1. Photoautotrophs: Convert sunlight into food via chloroplasts.

  2. Heterotrophs: Ingest food particles from the environment.

  3. Mixotrophs: Ingest and use sunlight for food.

Methods of Movement

  1. Pseudopods: False feet (ex. amoeba).

  2. Cilia: Short, hair-like projections (ex. paramecium).

  3. Flagella: Long, hair-like projections (ex. Leishmania).

  4. Passive movement via wind/water currents & using a host (ex. Plasmodium).

Further Classification of Protists

  • Three Lifestyles:

    • Plant-like Protists

    • Animal-like Protists

    • Fungus-like Protists

A) Plant-like Protists

  • Commonly known as algae.

  • Contain chlorophyll; perform photosynthesis.

  • Majority are autotrophs; some are mixotrophs.

  • Reproduce sexually and asexually.

  • Live in moist environments (ponds).

  • Key to aquatic food webs (e.g., dinoflagellates).

4 Groups of Plant-like Protists

  1. Euglenoids: Photosynthetic; can become heterotrophs in the dark.

  2. Diatoms: Silica cell walls; important marine food source.

  3. Dinoflagellates: Unicellular, cellulose cell walls, two flagella.

  4. Algae: Various phyla including green, brown, red, and golden algae.

Harmful Algal Blooms

  • Rapid reproduction of algae due to increased temperature/rainfall.

  • Red tide: Caused by dinoflagellate blooms; toxins can contaminate shellfish.

B) Animal-like Protists (Protozoans)

  • Unicellular, reproduce via binary fission.

  • Heterotrophs that ingest food.

  • Groups include:

    • Cercozoans (Amoebas)

    • Ciliates (ex. Paramecium)

    • Flagellates (ex. Leishmania)

    • Sporozoans (parasites, e.g., causes malaria).

C) Fungus-like Protists

  • Resemble fungi; differ at the cellular level.

  • Heterotrophs, decomposers (feed on bacteria and decaying organic matter).

  • Reproduce asexually through spores.

  • Groups include:

    • Cellular slime molds

    • Plasmodial slime molds

    • Water molds (caused the Irish Potato Famine).

Impact on Human Health

  • Plasmodium: Causes malaria, transmitted by mosquitoes.

  • Life cycle involves infection of human blood cells.

  • Symptoms include fever, chills; leads to severe health effects.

  • Antimalarial drugs: Chloroquine; resistance varies by region.

Study Reminders

  • Prepare for the Unit Test.

  • Complete the gonorrhea assignment.