Plant Cell Biology: Cell Structure, Ergastic Substances, and Plastid Differentiation

Comprehensive vocabulary flashcards covering plant cytology, endosymbiosis, algal and diatom anatomy, cell wall thickenings, ergastic calcium oxalate crystals, plastid differentiation, and starch and protein storage structures.

Styloid (Iris germanica)

An elongated, single prismatic or rod-like calcium oxalate crystal found accumulated within the vacuolar sap of plant cells such as Iris germanica.

Raphides (Tradescantia zebrina)

Needle-shaped calcium oxalate crystals that typically occur in dense bundles within specialized plant cell vacuoles, characteristic of Tradescantia zebrina.

Druses (Begonia vitifolia / Juglans regia)

Spherical, rosette-like polycrystalline aggregates of calcium oxalate that form within plant cell vacuoles, found in species such as Begonia vitifolia and Juglans regia.

Crystal Sand (Nicotiana tabacum)

A fine mass composed of thousands of minute microcrystalline calcium oxalate particles filling specialized cells, found in the leaf parenchyma of Nicotiana tabacum.

Cystolith (Ficus elastica)

An internal, centripetal localized outgrowth and thickening of the cell wall that becomes heavily encrusted with calcium carbonate, characteristic of epidermal cells in Ficus elastica.

Pitted Cell Wall Thickening (Clematis vitalba)

A form of secondary cell wall thickening traversed by simple pits across horizontal and vertical cell walls, separated by the middle lamella, found in stem parenchyma cells of Clematis vitalba.

Exine Sculpturing (Pollen Wall)

Centrifugal (external) localized thickenings and spine-like projections developed on the outer sporoderm layer (exine) of pollen grains in plants such as Cucurbita pepo and Hibiscus syriacus.

Endosymbiotic Theory

The evolutionary model proposing that eukaryotic organelles originated when ancestral prokaryotes engulfed aerobic heterotrophic proteobacteria (forming mitochondria) and photosynthetic cyanobacteria (forming chloroplasts).

Prokaryotic Cell

A cellular structural type lacking a membrane-bound nucleus and endomembrane organelles, represented by bacteria and cyanobacteria, featuring circular DNA in a nucleoid, plasmids, small ribosomes, and a peptidoglycan cell wall.

Plant Cell vs. Animal Cell Differences

Plant cells uniquely possess a cellulose cell wall, plastids (chloroplasts), and a large central vacuole, whereas animal cells lack cell walls and chloroplasts and uniquely contain centrioles and prominent lysosomes.

Desmids (Conjugatophyceae)

Unicellular green algae, including Cosmarium, Euastrum, and Micrasterias, characterized by bilateral symmetry with two semi-cells joined at a central constriction termed an isthmus.

Isthmus

The narrow central connecting zone between the two symmetrical semi-cells of desmid algae like Cosmarium, Euastrum, and Micrasterias.

Pinnularia sp.

A genus of elongated pennate diatoms whose siliceous frustule features a central longitudinal raphe, prominent transverse ribs (costae), and central and polar nodules.

Triceratium sp.

A marine centric diatom with a triangular siliceous shell possessing distinctive angular thickenings at each corner and warty (verrucose) surface wall ornamentations.

Chloroplast

A double-membrane photosynthetic organelle containing chlorophyll pigments, plastid DNA, ribosomes, and an internal thylakoid network organized into grana within the stroma.

Pyrenoid

A specialized proteinaceous sub-organelle located within algal chromatophores and chloroplasts that serves as the center for starch synthesis and accumulation.

Chromatophore (Algae)

The pigment-bearing photosynthetic apparatus of algal cells found in distinct morphologies, such as spiral ribbon-like bands in Spirogyra or stellate shapes in Zygnema.

Granular Chloroplasts (Elodea canadensis)

Numerous small, disc- or grain-shaped chloroplasts distributed within the photosynthetic cells of the aquatic plant Elodea canadensis.

Prosenchyma vs. Parenchyma (Mnium)

Two cell arrangements observed in mosses like Mnium, where prosenchyma consists of elongated, narrow cells with tapered ends (forming leaf borders) and parenchyma consists of isodiametric metabolic cells.

Cytoplasmic Streaming (Tradescantia virginica)

The continuous, active movement of cytoplasm and suspended organelles along transvacuolar strands, clearly demonstrated in the stamen hairs of Tradescantia virginica.

Plastids

A family of double-membrane bound organelles found in plant and algal cells that contain circular DNA and ribosomes, derived from cyanobacterial ancestors via endosymbiosis.

Proplastid

An undifferentiated, small, colorless precursor plastid found in meristematic tissues that develops into etioplasts, chloroplasts, chromoplasts, or leucoplasts depending on cellular signals and light exposure.

Chromoplast

A plastid containing red, orange, or yellow carotenoid pigments that provides pigmentation to flowers and fruits to attract pollinators and aid seed dispersal.

Crystalline Carotenoidoplasts (Daucus carota)

A subtype of chromoplast in which carotenoid pigments precipitate into rigid, angular crystalline plates or needle-like sheets, characteristic of carrot roots (Daucus carota).

Fibrillar Carotenoidoplasts (Solanum lycopersicum)

A subtype of chromoplast in which carotenoid pigments are incorporated into elongated, thread-like protein-lipid fibrils, characteristic of tomato fruit mesocarp (Solanum lycopersicum).

Leucoplast

A non-pigmented, colorless plastid specialized for nutrient synthesis and storage, observed in leaf epidermal peels of Tradescantia zebrina as well as in underground roots and seeds.

Amyloplast

A specialized category of leucoplast dedicated to the synthesis and storage of starch granules in non-photosynthetic plant tissues.

Potato Starch Grains (Solanum tuberosum)

Large, simple, oval or clam-shaped starch grains with an eccentric (off-center) hilum surrounded by distinct concentric rings of crystalline and amorphous regions.

Bean Starch Grains (Phaseolus vulgaris)

Simple oval-to-kidney-shaped starch grains exhibiting a prominent longitudinal or branching central radial fissure in the cotyledons of Phaseolus vulgaris.

Aleurone Layer (Triticum vulgare)

A specialized peripheral protein-storing cell layer of cereal endosperm located beneath the pericarp and seed coat in Triticum vulgare, enclosing the inner starchy endosperm.

Corn Starch Grains (Zea mays)

Simple, angular or polygonal starch granules with a distinctive central star-shaped (stellate) fissure, found in the endosperm of Zea mays.

Compound Starch Grains (Oryza sativa)

Large ovate compound starch complexes composed of numerous small, polyhedral, tightly aggregated granules, characteristic of rice endosperm (Oryza sativa).

Bone-shaped Starch Grains (Euphorbia splendens)

Elongated rod-like starch grains featuring swollen, dumbbell- or bone-like ends, characteristic of the latex of Euphorbia splendens.

Complex Aleurone Grains (Ricinus communis)

Protein storage bodies in the endosperm of oil seeds (Ricinus communis) that contain an amorphous protein matrix enclosing a polygonal protein crystalloid and a rounded mineral-protein globoid.