BoO Ch. 28 - Protists

Alga

A general term for any species of photosynthetic protist, including both unicellular and multicellular forms; species are included in three eukaryote supergroups (Excavata, SAR, and Archaeplastida)

Alternation of generations

A life cycle in which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte; characteristic of plants and some algae.

Alveolates

One of the three major subgroups for which the SAR eukaryotic supergroup is named. This clade arose by secondary endosymbiosis, and its members have membrane-enclosed sacs (alveoli) located just under the plasma membrane

Amoeba

A protist characterized by the presence of pseudopodia

Amoebozoan

A protist in a clade that includes many species with lobe- or tube-shaped pseudopodia

Apicomplexan

A group of alveolate protists, this clade includes many species that parasitize animals. Some apicomplexans cause human disease

Archaeplastida

One of four supergroups of eukaryotes proposed in a current hypothesis of the evolutionary history of eukaryotes. This monophyletic group, which includes red algae, green algae, and plants, descended from an ancient protistan ancestor that engulfed a cyanobacterium

Blade

A leaflike structure of a seaweed that provides most of the surface area for photosynthesis

brown alga

A multicellular, photosynthetic protist with a characteristic brown or olive color that results from carotenoids in its plastids. Most are marine, and some have a plant-like body

Cercozoan

An amoeboid or flagellated protist that feeds with threadlike pseudopodia

Ciliate

A type of protist that moves by means of cilia

Conjugation

In ciliates, a sexual process in which two cells exchange haploid micronuclei but do not reproduce

Consumer

An organism that feeds on producers, other consumers, or nonliving organic material

Diatom

hotosynthetic protist in the stramenopile clade; have a unique glass-like wall made of silicon dioxide embedded in an organic matrix

Dinoflagellate

A member of a group of mostly unicellular photosynthetic algae with two flagella situated in perpendicular grooves in cellulose plates covering the cell

Diplomonad

A protist that has modified mitochondria, two equal-sized nuclei, and multiple flagella

Endosymbiosis

A relationship between two species in which one organism lives inside the cell or cells of another organism; The theory that mitochondria and plastids originated as prokaryotic cells engulfed by a host cell. The engulfed cell and its host cell then evolved into a single organism

Euglenid

A protist characterized by an anterior pocket from which one or two flagella emerge

Euglenozoan

A member of a diverse clade of flagellated protists that includes predatory heterotrophs, photosynthetic autotrophs, and pathogenic parasites.

Excavata

One of four super-groups of eukaryotes proposed in a current hypothesis of the evolutionary history of eukaryotes; have unique cytoskeletal features, and some species have an “excavated” feeding groove on one side of the cell body

foram (foraminiferan)

An aquatic protist that secretes a hardened shell containing calcium carbonate and extends pseudopodia through pores in the shell

green alga

A photosynthetic protist, named for green chloroplasts that are similar in structure and pigment composition to the chloroplasts of plants; a paraphyletic group; some members are more closely related to plants than they are to other members of the group

Heteromorphic

Referring to a condition in the life cycle of plants and certain algae in which the sporophyte and gametophyte generations differ in morphology

Holdfast

A rootlike structure that anchors a seaweed

Isomorphic

Referring to alternating generations in plants and certain algae in which the sporophytes and gametophytes look alike, although they differ in chromosome number

Kinetoplastid

A protist, such as a trypanosome, that has a single large mitochondrion that houses an organized mass of DNA

Mixotroph

An organism that is capable of both photosynthesis and heterotrophy

Opisthokont

A member of an extremely diverse clade of eukaryotes that includes fungi, animals, and several closely related groups of protists

Parabasalid

A protist, such as a trichomonad, with modified mitochondria

Producer

An organism that produces organic compounds from carbon dioxide by harnessing light energy (in photosynthesis) or by oxidizing inorganic chemicals (in chemosynthetic reactions carried out by some prokaryotes)

Protist

An informal term applied to any eukaryote that is not a plant, animal, or fungus; most are unicellular, though some are colonial or multicellular

Pseudopodia

A cellular extension of amoeboid cells used in moving and feeding

Radiolarian

A protist, usually marine, with a shell generally made of silica and pseudopodia that radiate from the central body

red alga

A photosynthetic protist, named for its color, which results from a red pigment that masks the green of chlorophyll. Most are multicellular and marine.

Rhizarians

One of the three major subgroups for which the SAR eukaryotic supergroup is named. Many species in this clade are amoebas characterized by threadlike pseudopodia

SAR

Includes three large clades: Stramenopila, Alveolata,

and Rhizaria

Secondary Endosymbiosis

A process in eukaryotic evolution in which a heterotrophic eukaryotic cell engulfed a photosynthetic eukaryotic cell, which survived in a symbiotic relationship inside the heterotrophic cell.

Stipe

A stemlike structure of a seaweed.

Stramenopiles

One of the three major subgroups for which the SAR eukaryotic supergroup is named. This clade arose by secondary endosymbiosis and includes diatoms and brown algae

Test

In foram protists, a porous shell that consists of a single piece of organic material hardened with calcium carbonate

Unikonta

One of four supergroups of eukaryotes proposed in a current hypothesis of the evolutionary history of eukaryotes. This clade, which is supported by studies of myosin proteins and DNA, consists of amoebozoans and opisthokonts