Chapter 28 - Protists: The First Eukaryotes

Vocabulary flashcards covering key Protist concepts from Chapter 28.

Protists

A diverse group of mostly single-celled eukaryotes; not a single kingdom; includes producers and heterotrophs.

Endosymbiosis

A process where one cell lives inside another; explains origin of organelles like mitochondria and plastids.

Primary endosymbiosis

An ancestral eukaryote engulfs a cyanobacterium, giving rise to plastids (chloroplasts) and mitochondria in the lineage.

Secondary endosymbiosis

A eukaryote engulfs a photosynthetic eukaryote (green/red alga), leading to plastids with extra membranes.

Mitochondria

Energy-producing organelle derived from engulfed aerobic prokaryote.

Nucleus

Membrane-bound organelle formed by invagination of the cell membrane; houses DNA.

Chloroplast

Plastid responsible for photosynthesis; derived from cyanobacteria via primary endosymbiosis.

Cyanobacteria

Photosynthetic bacteria; ancestral source of plastids in plants and algae.

Dinoflagellates

Protists with two opposite flagella; major phytoplankton; can form red tides and produce toxins.

Phytoplankton

Microscopic photosynthetic organisms floating near the surface; base of aquatic food webs.

Producers

Organisms that perform photosynthesis to create organic matter used by others.

Heterotroph

Organisms that obtain carbon by consuming organic molecules.

Mixotroph

Organisms capable of both photosynthesis and heterotrophy.

Pseudopodia

Temporary cytoplasmic extensions used for movement and feeding by some protists.

Cilia

Short, hair-like projections used for locomotion in some protists.

Flagella

Long, whip-like appendages used for movement; dinoflagellates often have two.

Osmoregulation

Regulation of water and solute balance in cells.

Contractile vacuole

Organelle that collects and expels excess water to maintain osmotic balance.

Alternation of generations

Life cycle switching between haploid gametophyte and diploid sporophyte stages.

Gametophyte

Multicellular haploid stage that produces gametes.

Sporophyte

Multicellular diploid stage that produces spores by meiosis.

Haploid

Cells with one set of chromosomes.

Diploid

Cells with two sets of chromosomes.

SAR

A major eukaryotic supergroup containing Stramenopiles, Alveolates, and Rhizaria.

Excavata

A supergroup of unicellular eukaryotes with a feeding groove; includes euglenids and diplomonads.

Archaeplastida

Supergroup including red and green algae and land plants; derived from primary endosymbiosis.

Unikonta

Supergroup including Amoebozoa and Opisthokonta (fungi and animals).

Amoebozoa

Amoeboid protists with lobe- or tube-shaped pseudopodia.

Opisthokonta

Clade including animals, fungi, and related protists.

Diatom

Stramenopile; photosynthetic algae with silica cell walls; common in oceans and freshwater.

Green algae

Photosynthetic algae within Archaeplastida; ancestors of land plants.

Red algae

Photosynthetic algae within Archaeplastida with phycoerythrin pigment enabling deeper light absorption.

Red tide

Bloom of dinoflagellates causing water to appear red and sometimes toxin production.

Saxitoxin

Potent neurotoxin produced by some dinoflagellates during harmful algal blooms.

Phylogeny

Evolutionary history and relationships among organisms.