A Walk Through Time A Walk Through Time AssignmentsAssignments

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““Protista”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 ProtistsEcology 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 cellThe Eukaryotic cell

Paramecium, a ciliated protozoan

This view is under Nomarski phase contrast

Eukaryotic vs. prokaryotic cellsEukaryotic vs. prokaryotic cells

• Size* Prokaryotes ≤ 10 µm* Eukaryotes ≥ 10 µm

• Complexity* Prokaryotes – simple* Eukaryotes – complex

• Location of chromosomes* Prokaryotes – free in cytosol* Eukaryotes – within a nucleus

• Flagellar mechanisms differ

Bacteria & Archea

protists, Fungi, Plants, Animals

Bacterium (prokaryote)

Animal (eukaryote)

Plant (eukaryote)

Figures 7.4, 7.7, 7.8

(Actual size relative to eukaryotes below)

Protista as a single “kingdom”Protista as a single “kingdom”Functional gFunctional groupsroups

• Algae – photosynthetic• Protozoa – non photosynthetic, consumers• Fungus-like Protists – nonphotosynthetic,

hyphal

• Each group is polyphyletic

““Protozoa”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)

PseudopodiaPseudopodia

Movie of Pseudopodial movement in Amoeba

PseudopodiaPseudopodia

Actinophrys

FlagellaFlagella

Paranema

FlagellaFlagella

Giardia

CiliaCilia

Paramecium

Macronucleusw/ micronuclei

behind

Oral groove on surface

Site of cell “anus”

Food vacuoles

Cilia

Undulating membrane in groove (ciliary)

Contractile vacuoles

Paramecium, a ciliated protozoan

CiliaCilia

Euplotes