Unit 3: Protists and Origin of Eukaryotic Cells - Vocabulary

Vocabulary flashcards covering key terms from Unit 3 notes on origin of eukaryotic cells and protists.

Endosymbiosis

The theory that mitochondria and chloroplasts originated as free-living bacteria engulfed by a host cell and evolved into organelles.

Mitochondrion

Organelle formed by endosymbiosis with a proteobacterium; the cell’s main source of ATP.

Chloroplast

Organelle formed by endosymbiosis with cyanobacteria; site of photosynthesis in plants and algae.

Proteobacterium

Ancestor bacterium that was engulfed to form the mitochondrion through endosymbiosis.

Cyanobacteria

Photosynthetic bacteria that contributed to the origin of chloroplasts via endosymbiosis.

Infolding of the cell membrane

Inward folding of the plasma membrane that increases surface area and forms internal membrane systems.

Nucleus

Membrane-bound organelle enclosing the cell’s DNA; formed when infolded membranes enclosed genetic material.

Cytoskeleton

Network of microfilaments and microtubules providing structural support and organization in the cell.

Digestive vacuole

Early intracellular compartment for digestion; later evolved into lysosomes, aided by enzymes from the ER.

Lysosome

Digestive organelle containing enzymes; derived from digestive vacuoles in early eukaryotes.

Paramecium

Unicellular ciliate with a slipper shape; uses cilia for movement; contains macronucleus and micronucleus.

Macronucleus

Large nucleus in ciliates that controls non-reproductive cell functions.

Micronucleus

Small nucleus in ciliates involved in genetic exchange during conjugation.

Contractile vacuole

Organelle that expels excess water to maintain osmotic balance in some protists.

Pellicle

Flexible layer beneath the cell membrane in many protists that helps maintain shape.

Cilia

Short hairlike structures used for locomotion and feeding in many protists.

Alveolates

Protist group characterized by alveolar sacs just beneath the plasma membrane; includes dinoflagellates, apicomplexans, and ciliates.

Dinoflagellates

Alveolates that are mostly marine, with two flagella and carotenoid pigments; often photosynthetic and can cause red tides.

Red tide

Harmful algal bloom caused by dinoflagellate toxins; can poison seafood and affect humans.

Ciliates

Alveolates with numerous cilia; include Paramecium; possess macronucleus and micronucleus, plus contractile vacuole and pellicle.

Di​atoms

Stramenopiles that are unicellular autotrophs with silica cell walls and carotenoid-containing chloroplasts.

Brown algae

Large multicellular stramenopiles (kelp) with holdfast, stipe, blades, and pneumatocysts; marine.

Holdfast

Root-like structure that anchors brown algae to the substrate.

Stipe

Stem-like stalk of brown algae supporting the blades.

Blades

Leaflike portions of brown algae where photosynthesis occurs.

Pneumatocyst

Gas-filled bladder in brown algae that provides buoyancy.

Alginic acid

Polysaccharide in brown algae cell walls used as a thickener and stabilizer.

Diatomaceous earth

Sedimentary deposit formed from fossilized diatoms; used commercially and geologically.

Oomycetes

Water molds; part of the Stramenopiles; often similar to fungi in lifestyle.

Euglenids

Excavates that are unicellular with flagella and an eyespot; mixotrophic or photosynthetic.

Giardia

Giardia muris, a diplomonad excavate with two nuclei and multiple flagella; parasitic.

Amoebozoans

Group of protists with lobose-shaped pseudopods; includes amoebas and slime molds.

Loboseans

Amoebozoans such as Amoeba with lobed pseudopods used for feeding and movement.

Plasmodial slime molds

Slime molds forming a single multinucleate plasmodium that can grow large.

Cellular slime molds

Slime molds that exist as individual amoebae and aggregate to form fruiting bodies.

Binary fission

Asexual division where a single cell divides into two identical daughter cells.

Conjugation

Sexual process in ciliates involving exchange of genetic material without reproduction.

Alternation of generations

Life cycle alternating between haploid and diploid multicellular generations.

Coral bleaching

Loss of dinoflagellate endosymbionts in corals, often due to stress, leading to whitening and potential death.