A Walk Through Time
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“Protista”
One-celled to simple colonies to plant-like (but
these related to simple forms)
Cells eukaryotic
Photosynthetic and heterotrophic metabolisms
Now usually split into several kingdoms
Not plants, fungi, nor animals
Spirogyra
Amoeba
Ecology of the Protists
• Though small, play major roles
* 65 % of earth’s net primary production
(phytoplankton)
* Microfeeders of bacteria, other protists
* Food for larger plankton & animals
* Habitats for other organisms
* Decomposers
* Parasites of plants and animals
The Eukaryotic cell
Paramecium, a ciliated protozoan
This view is under Nomarski phase contrast
Eukaryotic vs. prokaryotic cells
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Size
* Prokaryotes ≤ 10 µm
* Eukaryotes ≥ 10 µm
Bacteria & Archea
protists, Fungi, Plants, Animals
Complexity
* Prokaryotes – simple
* Eukaryotes – complex
Location of chromosomes
* Prokaryotes – free in cytosol
* Eukaryotes – within a nucleus
Flagellar mechanisms differ
Figures 7.4, 7.7, 7.8
Bacterium
(prokaryote)
(Actual size relative to
eukaryotes below)
Animal
(eukaryote)
Plant
(eukaryote)
Protista as a single “kingdom”
Functional groups
• Algae – photosynthetic
• Protozoa – non photosynthetic, consumers
• Fungus-like Protists – nonphotosynthetic,
hyphal
• Each group is polyphyletic
“Protozoa”
• Protista that are heterotrophic by injestion
• Motile
* pseudopodia – amoebas
* flagella – flagellates
* cilia – ciliates
• Ancent and advanced groups
• Polyphyletic (i.e. phyla not closely related)
Pseudopodia
Movie of Pseudopodial movement in Amoeba
Pseudopodia
Actinophrys
Flagella
Paranema
Flagella
Giardia
Cilia
Paramecium
Undulating membrane in groove
(ciliary)
Food vacuoles
Oral groove on surface
Macronucleus
w/ micronuclei
behind
Cilia
Contractile
vacuoles
Paramecium, a ciliated protozoan
Site of cell “anus”
Cilia
Euplotes