Protists Lecture Review

Flashcards covering the classification, nutrition, morphology, and specific groups of protists including Excavata, Amoebozoa, and Archaeplastida.

Protists

A diverse, polyphyletic collection of over $64,000$ different eukaryotic single-celled life forms that lack the level of tissue organization present in higher eukaryotes.

Saprophytes

Chemoheterotrophic protists that obtain nutrients from dead organic matter through enzymatic degradation.

Osmotrophy

The process by which protists absorb soluble products for nutrition.

Holozoic nutrition

A method of nutrition where solid nutrients are acquired by phagocytosis.

Mixotrophic protists

Protists that use organic and inorganic carbon compounds simultaneously.

Ectoplasm

The outer gelatinous region of the cytoplasm located just underneath the plasma membrane.

Endoplasm

The inner fluid region of the cytoplasm in a protist.

Pellicle

A structure that provides support to the plasma membrane in protist morphology.

Contractile vacuoles

Organelles that help maintain osmoregulation by pushing out excess water to prevent osmotic stress.

Hydrogenosomes

Organelles used for energy production in anaerobic chemoorganotrophs.

Encystment

The process where a protist simplifies its structure and becomes a dormant cyst with a cell wall and low metabolic activity to protect against environmental changes.

Excystment

The return to a vegetative state from a cyst form, often stimulated by favorable conditions or ingestion by a new host.

Syngamy

The sexual reproduction process in protists involving the fusion of gametes.

Autogamy

A type of sexual reproduction occurring within a single individual.

Conjugation

The sexual exchange of gametes between two individuals.

Super-Group Excavata

A group of primitive eukaryotes characterized by a suspension-feeding groove/feeding pocket used to capture particles.

Mitosomes

Mitochondria-like double-membrane bounded organelles found in members of the Fornicata like Giardia.

Trichonymphida

Obligate mutualists of wood-eating insects that release cellulose to digest wood and can account for $1/3$ of a termite's biomass.

Trichomonas vaginalis

A pathogenic parabasilian that causes trichomoniasis, a sexually transmitted infection with approximately $180 ext{ million}$ cases worldwide.

Stigma

A red eye spot found in Euglenozoa used to orient the organism toward light.

Trypanosoma cruzi

The parasite transmitted by "kissing bugs" that causes Chagas’ disease and damages the nervous system.

Antigenic variation

A mechanism used by Trypanosomes to escape the host immune system by changing their thick glycoprotein layer.

Amoeboid motility

Locomotion and feeding through the use of pseudopodia, including lobopodia (rounded), filopodia (long/narrow), and reticulopodia (netlike mesh).

Entamoeba histolytica

A parasite that causes amoebic dysentery, the third leading cause of parasitic death worldwide, acquired via cyst ingestion.

Myxogastria

Acellular slime molds characterized by a plasmodium that lacks a cell membrane and can contain up to $10,000$ dividing nuclei.

Dictyostelia

Cellular slime molds that exist as individual amoeboid cells but can aggregate into a multicellular mass called a pseudoplasmodium when starved.

Sentinel cells

Cells in cellular slime molds that differentiate to resemble primitive immune cells and patrol for pathogenic bacteria.

Foraminifera

Marine protists with reticulopodia and tests made of calcium carbonate that form modern-day chalk, limestone, and marble.

Dinoflagellates

A large group of marine plankton responsible for phosphorescence and toxic blooms; some live as zooxanthellae in corals.

Apicomplexans

Parasitic protists distinguished by a unipolar apical complex; includes Plasmodium, the cause of malaria.

Frustule

The unique, two-piece cell wall of silica found in diatoms.

Archaeplastida

A supergroup containing organisms with photosynthetic plastids derived from an ancient endosymbiosis with a cyanobacterium.

Chlamydomonas

A member of Chlorophyta with a haploid nucleus, a large chloroplast, and two contractile vacuoles for osmoregulation.