The Protists Review Flashcards

This set explores the diverse characteristics, evolutionary origins, and classification of protists, covering the 4 major eukaryotic supergroups.

Protists

The informal name for mostly microscopic eukaryotic organisms that emerged during evolution, with fossils dating back to $2.1\,\text{billion years}$ and chemical signatures to $2.7\,\text{billion years}$.

Mixotrophs

Protists that combine photosynthesis and heterotrophic nutrition, such as Euglena.

Protozoa

An ecological category consisting of ingestive, animal-like protists.

Plankton

Communities of organisms that drift passively or swim weakly in water, which include many protists.

9 + 2 microtubule system

The structural system of microtubules that supports eukaryotic flagella, which are extensions of the cytoplasm.

Syngamy

The union of two gametes that occurs during the sexual reproduction of many protists.

Serial Endosymbiosis

A theory proposing that mitochondria and chloroplasts originated as small prokaryotes living within larger host cells.

Autogenesis

A process by which the eukaryotic endomembrane system may have evolved from infoldings of the plasma membrane.

Excavata

A clade of protists characterized by cytoskeleton similarities, modified mitochondria or flagella, and often an excavated feeding groove.

Diplomonads

A group within Excavata that possesses modified mitochondria called mitosomes, lacks electron transport chains, and has two equal-sized nuclei.

Parabasalids

Excavates with reduced mitochondria called hydrogenosomes that generate energy anaerobically; an example is Trichomonas vaginalis.

Euglenozoans

A diverse clade that includes predatory heterotrophs and photosynthetic autotrophs, distinguished by a spiral or crystalline rod inside their flagella.

Paramylon

A unique glucose polymer used as a storage molecule in Euglenozoans.

Kinetoplastids

A group in Euglenozoa having a single mitochondrion with an organized mass of DNA called a kinetoplast, including the genus Trypanosoma.

SAR clade

A diverse monophyletic supergroup defined by DNA similarities, including Stramenopiles, Alveolates, and Rhizarians.

Stramenopila

A sub-supergroup of protists named for having numerous fine, hairlike projections on one of their flagella, usually paired with a smooth flagellum.

Diatoms (Bacillariophyta)

Unicellular algae with unique glasslike walls composed of hydrated silica embedded in an organic matrix.

Golden algae (Chrysophyta)

Typically biflagellated protists named for their yellow and brown carotene photosynthetic pigments.

Brown algae (Phaeophyta)

Large, complex, and mostly multicellular algae that owe their color to carotenoid pigments in their plastids.

Alternation of Generations

A life cycle involving the alternation between multicellular haploid and diploid forms.

Oomycetes

Water molds and their relatives that were misidentified as fungi but have cell walls made of cellulose and multinucleate filaments.

Alveolata

A sub-supergroup of protists characterized by small membrane-bound cavities called alveoli under the cell surface.

Dinoflagellates

Abundant phytoplankton components with shapes reinforced by cellulose plates and two flagella that produce a spinning movement.

Apicomplexans

Animal parasites, like Plasmodium, that disseminate as sporozoites and have a complex of organelles for penetrating host cells.

Ciliophora (ciliates)

Protists that use cilia to move and feed, characterized by having a large macronucleus and several tiny micronuclei.

Rhizarians

A clade of protists, many of which are amoebas, that move and feed using threadlike pseudopodia.

Foraminiferans (forams)

Rhizarians named for their porous, multichambered shells called tests.

Radiolarians

Marine protists with tests fused into one delicate piece made of silica and radiating pseudopodia used for phagocytosis.

Archaeplastida

A supergroup including red algae, green algae, and land plants, descended from an ancient protist that acquired a cyanobacterial endosymbiont.

Unikonta

A supergroup that includes animals, fungi, and amoebozoans, characterized by lobe- or tube-shaped pseudopodia in the amoeboid members.