Cell types
| Collenchyma: | elongate cells with thickened primary wall facing intercellular spaces, having immature plastids, but otherwise like parenchyma |
| Meristematic: | undergoing cell divisions, typically small and thin-walled, lacking mature plastids or vacuoles. |
| Parenchyma: | thin-walled, complex cytoplasm, active biochemistry, sometimes isodiametric, sometimes with large intercellular spaces |
| Sclerenchyma: | cells with heavy, lignified secondary walls, usually dead at maturity, protoplast missing. |
| Amyloplast: | a colorless plastid consisting mostly of starch (amylose) |
| Cell membrane= plasma membrane: | a phospholipid bilayer including intrinsic and extrinsic proteins for facilitated diffusion and active transport |
| Chloroplast: | a mature plastid developing grana stacks of thylakoid membranes holding chlorophyll; responsible for photosynthesis |
| Chromoplast: | a plastid with membranes holding primarily yellow or orange carotenoid pigments instead of chlorophyll |
| Cristae: | inner membrane of mitochondrion folded and specialized for oxidative phosphorylation and the electron transport system |
| Cytoplasm: | all fluids and organelles of the cell found inside the cell membrane, but usually not including the nucleus |
| Cytosol: | the fluid surrounding the organelles consisting of water and dissolved solutes, notably enzymes, substrates, and products; responsible for glycolysis and fermentation |
| Endoplasmic reticulum: | the endomembrane system responsible for movement of materials from one area of a cell to another, sometimes for membrane synthesis, sometimes studded with ribosomes on its cytosolic face |
| Golgi apparatus= dictyosome: | a stack of endoplasmic reticulum membranes responsible for sorting and packaging cell products for export via vesicles |
| Leucoplast: | a colorless plastid |
| Matrix: | the fluid inside the mitochondrion, containing 70S ribosomes; naked, circular DNA; and responsible for the Krebs cycle (Citric Acid cycle, TCA cycle) |
| Microfilament: | a small-diameter fiber of the cytoskeleton composed of actin; responsible for certain types of cytoplasmic movements |
| Microsome= microbody: | small organelles of several types, including lysosomes, peroxysomes, glyoxysomes, etc. responsible for certain metabolic pathways or portions thereof |
| Microtubule: | a large-diameter fiber of the cytoskeleton composed of tubulin; responsible for chromosome movement during mitosis and meiosis, also involved with flagellar movement |
| Middle lamella: | a pectinaceous glue holding cells together |
| Mitochondrion: | organelle responsible for the Krebs cycle (Citric Acid cycle, TCA cycle), and Oxidative phosphorylation reactions of respiration |
| Nuclear envelope: | the bounding membrane of the nucleus, derived from and continuous with the endoplasmic reticulum |
| Nucleolus: | a dark-staining body inside the nucleus, believed to be the site of ribosomal RNA synthesis and ribosome-subunit assembly |
| Nucleus: | an organelle containing the genomic DNA for the cell, responsible for transcription and replication; involved in mitosis |
| Plasmodesma: | a cytoplasmic connection penetrating both walls of adjacent cells, probably the result of incomplete wall formation from a phragmoplast during cytokinesis |
| Plastid: | a class of organelles including chloroplasts, chromoplast, leucoplasts, amyloplasts, and proplastids |
| Primary cell wall: | a multi-layered containment for the cell consisting of cellulose fibers, cross-linked by hemicellulose and other polysaccharides, also including protein. |
| Proplastid: | the archetype form of plastids, can develop into one of several types of plastids |
| Protoplast: | a plant cell lacking a cell wall; the cell membrane and its contents |
| Ribosomes: | 80S particles consisting of RNA and protein, responsible for protein synthesis (translation); sometimes free-floating, sometimes associated with the endoplasmic reticulum |
| Secondary wall: | an additional wall produced inside the primary wall, usually in three layers, consisting of cellulose, cross-linking polysaccharides, and up to 50% lignin polymers |
| Stroma: | the fluid inside the chloroplast, containing 70S ribosomes; naked, circular DNA; and responsible for the carbon-fixation reactions (Calvin cycle) of photosynthesis |
| Thylakoid membrane: | a membrane system, usually forming grana stacks, and holding chlorophyll by means of intrinsic membrane proteins: responsible for the light reactions of photosynthesis |
| Tonoplast: | the vacuole membrane |
| Vacuole: | a fluid compartment inside plant cells bounded by the tonoplast; responsible for toxic waste processing and storage |
| Vesicles: | small membrane bound packages containing materials for import or export |
| Columella: | cells in the middle of the root cap responsible for gravity perception possibly by means of starch statoliths |
| Ground meristem: | a primary tissue maturing to become cortex |
| Protoderm: | a primary tissue maturing to become the dermal system |
| Provascular tissue= procambium: | a primary tissue maturing to become the vascular cylinder |
| Quiescent center: | a group of pseudo-meristematic cells just under the root cap which are perhaps the source of cells recruited into the meristem |
| Root apex: | meristem plus associated root cap |
| Root cap: | meristematic and parenchymatous layer over end of root tip, sloughing cells at the periphery, secreting mucilage |
| Root hair: | an extension of a single epidermal hair, increasing surface area and secreting protons to release mineral cations from clay particles |
| Root meristem: | a zone of meristematic cells just proximal to the quiescent center, responsible for adding cells to the length of the root. |
| Zone of cell division: | areas of mitotic division including the root meristem and the root cap |
| Zone of cell elongation: | areas of rapid cell elongation usually just proximal to the zone of cell division |
| Zone of cell maturation: | areas in which cells are maturing into xylem, phloem, root hairs, etc.; usually just proximal to the zone of cell division |
| Apical bud: | a the shoot apex consisting of the shoot meristem and its associated leaf primordia |
| Axillary bud= lateral bud: | a branch apex developing in the narrow angle between the stem and leaf primordium; may be dormant or active |
| Internode: | the portion of the stem between nodes; cell division (interstitial or intercalary) and cell elongation are likely to occur here to extend the shoot tip and increase the height of the plant |
| Leaf primordium: | an immature leaf |
| Node: | a layer across the stem at the level of leaf attachment; neither cell division nor cell elongation is not likely to occur |
| Primary tissues: | protoderm, ground meristem, provascular tissues (see under root tip above) |
| Shoot meristem= apical dome: | meristematic cells at tip of stem axis |
| Zones of cell division, elongation, and maturation: | in stems these areas are dispersed throughout the developing stem, rather than distributed sequentially along the length as in roots (see under Root tip, above) |
| Abaxial: | the surface facing away from the stem; in a leaf the lower epidermis |
| Acropetal: | developing upward, toward the apex |
| Adaxial: | the surface facing the stem; in a leaf, the upper epidermis |
| Apical dominance: | the apical bud producing hormones which keep the lateral (axillary) buds dormant |
| Apical growth: | increase in length by addition of new cells at the tip of a leaf primordium (to form petiole and midrib) |
| Apical: | near the apex |
| Basal: | near the surface of the soil |
| Basipetal: | developing downward, toward the base |
| Centrifugal: | developing from the inside outward (sometimes from apex downwards) |
| Centripetal: | developing from the outside inward (sometimes from bottom upwards) |
| Determinate growth: | growth which results in a "final" size that does not change for the remaining life of the organ; typical of many dicot leaves and certain stems |
| Indeterminate growth: | growth which continues indefinitely during the life of the plant; typical of certain stems and certain kinds of monocot leaves. |
| Intercalary growth: | increase in cell size and cell number in basal region of internode or leaf blade (as in grasses). |
| Interstitial growth: | increase in cell size and cell number throughout small, but fully formed leaf primordium to produce mature leaf size |
| Marginal growth: | increase in width by addition of new cells along the edges of a leaf primordium (to form blade) |
| Anaphase: | the third portion of mitosis in which the centromere dissociates and the microtubules from each end depolymerize to pull sister chromatids to opposite ends of the cell |
| Cytokinesis: | the division of the cytoplasm of a dividing cell to form two new cells; in plants accomplished by formation of a phragmoplast at the equator |
| G1: | the first gap of interphase in which a cell which has just completed division carries out normal biochemsitry and prepares for synthesis of DNA |
| G2: | the second gap of interphase in which the cell has completed replication of its DNA and is preparing for mitosis and cytokinesis; normal biochemistry occurs |
| Interphase: | a long portion of the cell cycle in which DNA is decondensed as chromatin, consisting of three portions: G1, S, G2 |
| Metaphase: | the second portion of mitosis in which the chromosomes are pushed to the equator of the cell by spindle fibers (microtubules) which elongate from the poles and attach to both sides of the centromere of each chromosome |
| Mitosis: | nuclear division consisting of prophase, metaphase, anaphase, and telophase; a diploid (2N, 4C) cell divides its chromatids into separate diploid nuclei (2N 2C) |
| Prophase: | the first portion of mitosis in which the chromosomes condense out of the chromatin, the nuclear envelope disappears, and the nucleolus disappears |
| S: | the synthesis portion of interphase during which the DNA of the nucleus is replicated; a diploid cell (2N) becomes 4C, a haploid cell (1N) becomes 2C; the copies are held together at a region eventually becoming the centromere |
| Telophase: | the final portion of mitosis in which the nuclear envelope reforms, the chromosomes decondense to form chromatin, and the nucleolus reappears |
This page © Ross E. Koning 1994.
The CBE citation style for this page would be: Koning, Ross E. 1994. "Cytology and Meristems Vocabulary". Plant Physiology Website. http://koning.ecsu.ctstateu.edu/plant_biology/cytomerivocab.html (your visit date)
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