Wize University Biology Textbook > Eukaryotes
Unicellular Protists
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Kingdom Protista
- Protista is paraphyletic
- The clade includes all groups except for 3
Exam Tip
For most courses you don't need to memorize the names of the Protist subgroups. Instead focus on what makes them unique and what behavior or structure enables this.
Excavata
- Highly variable
- Can be very pathogenic
- Trypanosoma brucei (sleeping sickness)
- Transmitted by tsetse flies
- affects the Central Nervous System
- Giardia lamblia (diarrhea)
- Drinking water contaminated with feces
- Can infect other animals as well
Ghiardia lambila
Dinoflagellets
- Reinforced cellulose plates as armor
- 2 flagella which make it spin
- Greek "dinos" = whirling
- Latin "flagellum" = whip
- Includes marine and freshwater plankton
- Over abundance of some species will create red tides: a harmful algal bloom
Chromalveolates
- Several groups only united by DNA
- Apicomplexans
- Parasitic Example: Plasmodium (malaria)
- Ciliates
- Full mobility (unlike other plankton)
- Heterotrophic
- Uses oral groove to eat bacteria and small protists
- Phagocytosis: engulfs prey to eat
- Reproduces using binary fission / conjugation Example: Paramecium
- Diatoms
- Unicellular algae
- Makes up a large portion of marine and freshwater plankton
- Membrane made out of silica
- Super strong: (can withstand 1.4 million kg/m2!!)
Paramecium
Practice: Protists
Which clade of protists is best characterized by the two flagella it uses to spin and move?
Practice: Protists
Which group of unicellular protist has an extremely hard outer membrane made of silica?
Practice: Protists
Which group of unicellular protists contains extremely pathogenic organisms, including those that cause Sleeping Sickness and Giardia?