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Learn about the fascinating world of protists - eukaryotic organisms distinct from animals, plants, and fungi. Discover their classification, importance, and unique characteristics.
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I. The Kingdom Protista A. What is a Protist? • Any eukaryote that is not an animal, plant, or fungus a. Eukaryote – any unicellular or multicellular organism that has a nucleus and other organelles within its cell or cells 2. Most unicellular, some multicellular.
II. Protists were the first eukaryotic organisms to evolve on Earth • Lynn Margulis- hypothesized first eukaryotic cell formed by a close relationship among several prokaryotes • Many scientists agree that animals and plants evolved from protists.
III. Classification of Protists • Classified by how they obtain food. Include: Animal-like, Plant-like, and Fungus-like protists
Animal-like IV. Protozoans- animal-like protists (Consumers) obtain food from environment (they eat). • Ex: Paramecium and Amoeba
Figure 20-5 A Ciliate Lysosomes - digestion Section 20-2 Trichosysts - protection Oral groove -mouth Gullet - stomach Anal Pore – waste removal Contractile Vacuole – water removal Micronucleus –Back up memory Cilia -movement Food Vacuoles – Store food Macronucleus – Daily functions Go to Section:
Contractile vacuole Nucleus Food vacuole An Amoeba Section 20-2 Pseudopods Go to Section:
B. Importance of Protozoa (Animal-like protists) 1. Cause many human diseases like African sleeping sickness and amoebic dysentery (diarrhea)
Blood culture of Trypanosoma – causes African Sleeping Sickness Fever, chills, neurological problems, coma, death Image contributed by Pr. J. Le Bras, Hôpital Bichat
Fungus-like V. Slime molds and Water molds- fungus-like protists are consumers that obtain food by external digestion (this is weird). Act like fungus, but cell structure is like protists, no chitin in cell walls
A. Importance of Fungus-Like Protists - Slime molds- important decomposers in forests and swamps - Water molds – decomposers in water, parasites on land. 1. Water mold Phytophthorainfestans caused the Great Potato Famine in Ireland in 1845.
Plant-like VI. Algae- plant-like protists (producers) use sunlight to make food through the process of photosynthesis. • Ex: Unicellular Algae and Multicellular Algae
Euglena Section 20-3 Carbohydrate storage bodies Chloroplast Gullet Pellicle - protection Contractile vacuole –water removal Nucleus Flagella- movement Eyespot- Detects light Go to Section:
B. Importance of Algae (plant-like protists) • UnicellularAlgae – all contain some type of chlorophyll, most contain accessory pigments used for photosynthesis. • Form the base of food chains in oceans as phytoplankton • Carry out the majority of earth’s photosynthesis – produce most of Earth’s oxygen
2. Algal blooms- huge masses of algae quickly deplete nutrients in water; algal cells quickly die in great numbers; their decay depletes the supply of oxygen in water; kills fish and invertebrates A. Red tides- blooms of algae that produce a potentially dangerous toxin- shellfish can become full of the toxin- if eaten can cause serious illness, paralysis, even death
C. Importance of Multi-cellular Algae • Food source for many sea animals. • Home or refuge for many sea animals (kelp forests and Sargasso sea). • Produce much of earth’s oxygen.
Human uses • Source of vitamin C and Iron.
Human uses • Source of vitamin C and Iron. • Wrap for sushi.
Human uses • Source of vitamin C and Iron. • Wrap for sushi. • Additive for ice cream, pudding, candy bars. • Chemicals from Algae used in plastics, waxes, deodorants, paints and lubricants. • Some chemicals extracted from algae used to treat ulcers, high blood pressure, etc.
Protists Section 20-1 are classified as animallike plantlike Funguslike called called called Slim molds Water molds protozoa algae s which which use Produce food by photosynthesis External digestion Take in food from environment and include Go to Section: Decomposers parasites
