Key Terms
Where they live
Freshwater, marine, damp soil, snow, digestive tracts of animals, vascular tissues of plants. Nearly everywhere.
Core idea
Eukaryotes evolved when one cell engulfed another, and the engulfed cell survived. Both cells benefited.
Primary plastids
2 membranes, circular DNA, cyanobacterial-type ribosomes; some retain remnant peptidoglycan wall (glaucophytes, Paulinel
Secondary plastids
3+ membranes; some have nucleomorphs; found in Excavates and Chromalveolates
Phagocytosis process
Cell membrane engulfs particle -> phagosome forms -> fuses with lysosome to form phagolysosome -> hydrolytic enzymes dig
Taxis
Movement toward or away from a stimulus. Phototaxis = movement toward light (uses eyespot as sensor).
Asexual reproduction
Binary fission (transverse or longitudinal), multiple fission, budding. Default mode when nutrients are available.
Sexual reproduction
Triggered by nutrient depletion or environmental stress. Involves meiosis and fertilization.
Cysts
Resistant resting stages formed during sexual reproduction. Metabolically inactive.
Glaucophytes
Retain remnant peptidoglycan wall between inner and outer plastid membranes. Rare; evidence of ancient origin.
Amoeba proteus
~500 µm; uses pseudopodia for movement and feeding.
Pelomyxa
Multinucleate amoeba; 10x larger than Amoeba proteus; lost mitochondria but replaced them with bacterial endosymbionts.
Slime molds
Two types, both produce spores, both resemble fungi (convergent evolution).
Choanoflagellates
Unicellular or colonial; single flagellum surrounded by collar of microvilli; collar filters bacteria for ingestion. Nea
Ecological role
Rhizarians contribute to the biological carbon pump — when they die, their tests sink to the ocean floor, locking away c