BIOL 111 Lab 5: The Protists

Vocabulary flashcards covering the taxonomy, structural adaptations, nutritional modes, motility types, and disease-causing representatives of protists from BIOL 111 Lab 5.

Protist

Any eukaryote that is not a plant, animal, or fungus; they represent multiple evolutionary lineages that are informally organized into eukaryotic supergroups rather than a single kingdom.

Eukaryotic Supergroups

Informal taxonomic categories used to classify protists because they represent diverse evolutionary lineages that do not fit into traditional taxonomic groupings.

Earliest Protists

The first known eukaryotes in the fossil record, which appeared approximately $1.5\text{ billion}$ years ago.

Colony (Unicellular)

An aggregation of single-celled organisms of the same species physically linked together (such as Scenedesmus), lacking true multi-tissue differentiation.

Multicellular Organism

An organism composed of multiple specialized cell types functioning collectively, such as Volvox.

Autotroph

An organism that exclusively produces its own food (most commonly through photosynthesis); its biomass also feeds heterotrophic organisms.

Heterotroph

An organism that relies solely on external food sources by consuming and ingesting live or dead plant, animal, bacterial, or fungal matter.

Mixotroph

An organism capable of combining both autotrophic and heterotrophic modes of nutrition, such as Euglena.

Primary Producers

Autotrophic organisms (such as terrestrial plants and aquatic phytoplankton) situated at the base of food chains that generate Earth's organic matter.

Phytoplankton

Unicellular photosynthetic aquatic protists that produce up to $50\%$ of atmospheric oxygen and over $50\%$ of Earth's organic matter, forming the base of oceanic food chains.

Motility

The biological capability of an organism or cell to move independently.

Cilia

Short, thread-like cellular projections that beat rhythmically to propel single-celled organisms through fluid, or to clear mucus in the respiratory tracts of mammals.

Flagella

Long, whip-like appendages used for locomotion that are typically fewer in number per cell than cilia, sometimes occurring as a single whip-like structure.

Pseudopodia

Temporary, cytoplasm-filled extensions of the flexible plasma membrane and cytoskeleton ('false feet') used by amoeboid cells for locomotion and prey capture.

Diatoms

Unicellular, non-motile photosynthetic phytoplankton protected by non-decaying silica cell walls composed of two interlocking halves; they account for $25\%$ of Earth's primary production.

Volvox

Multicellular freshwater green algae forming hollow spherical colonies composed of biflagellated vegetative (somatic) cells and specialized reproductive germ cells.

Euglena

A unicellular freshwater mixotrophic protist equipped with a flagellum, photosensitive eyespot, pellicle for cellular flexibility, and a feeding groove for nutrient ingestion.

Eyespot (Stigma)

A light-sensitive organelle found in Euglena that detects light direction and intensity for phototaxis.

Pellicle

A layer of interlocking protein strips located beneath the plasma membrane in Euglena that gives the cell flexibility and contractile movement.

Contractile Vacuole

A specialized organelle in freshwater protists that collects excess water entering from hypotonic environments and expels it to prevent cell lysis.

Phagocytosis

A nutritional process in heterotrophic protists in which cellular extensions engulf food particles to encapsulate them inside an internal food vacuole for enzymatic digestion.

Protozoans

A term referring to complex, single-celled heterotrophic protists (meaning 'first animal') that ingest food or decompose organic debris.

Amoeba

A unicellular freshwater heterotroph characterized by a flexible plasma membrane, internal silica skeleton, and pseudopodia used for locomotion and phagocytosis.

Paramecium

A unicellular ciliated heterotroph possessing a distinct oral groove for feeding, food vacuoles, contractile vacuoles, a macronucleus, and a micronucleus.

Tests (Foraminifera)

Porous, durable shells composed of calcium carbonate ($CaCO_3$) secreted by Foraminifera, through which pseudopodia emerge.

Foraminifera

Unicellular, heterotrophic marine protists with porous calcium carbonate shells (tests) and long pseudopodia that leave extensive fossil records dating back $70\text{--}75\text{ MYA}$.

Saprolegnia

A multicellular, filamentous heterotrophic water mold with cellulose cell walls that feeds absorptively on dead organic matter or acts as a parasite on freshwater fish.

Hyphae (Saprolegnia)

The branching, filamentous structures that comprise the vegetative body of the water mold Saprolegnia.

Zoosporangia

Asexual reproductive organs in Saprolegnia that produce and release motile, flagellated zoospores which disperse and germinate into new hyphae.

Oogonia and Antheridia

Sexual reproductive organs of Saprolegnia: oogonia produce non-motile eggs, while antheridia produce sperm nuclei that fertilize the eggs to form oospores.

Phytophthora infestans

A parasitic water mold species responsible for causing potato blight.

Plasmopara viticola

A parasitic water mold species responsible for causing downy mildew in grapevines.

Trypanosoma

A unicellular, flagellated heterotrophic parasite transmitted by Tsetse flies that infects host blood and brain tissue to cause African Sleeping Sickness (trypanosomiasis), which is $100\%$ fatal if untreated.

Tsetse Fly

The blood-feeding insect vector in tropical Sub-Saharan Africa responsible for injecting the parasitic protist Trypanosoma into mammalian hosts.

Plasmodium

A genus of unicellular parasitic protists transmitted by mosquito vectors that infect human red blood cells, causing malaria.