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89 Cards in this Set
- Front
- Back
cell wall
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The rigid outermost layer of the cells found in plants, some protists, and most prokaryotes,
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eukaryote
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[Gk. eu, good, + karyon, kernel]: A cell that has a membrane-bounded nucleus, membrane-bounded organelles, and chromosomes in which the DNA is associated with proteins; an organism composed of such cells. Plants, animals, fungi, and protists are the four groups of eukaryotes
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cell sap
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The fluid contents of the vacuole
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cellulose
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A carbohydrate that is the chief component of the cell wall in plants and some protists; an insoluble complex carbohydrate formed of microfibrils of glucose molecules attached end to end
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apical meristem
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The meristem at the tip of the root or shoot in a vascular plant
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cell division
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The division of a cell and its contents, usually into two roughly equal parts
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cell wall
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The rigid outermost layer of the cells found in plants, some protists, and most prokaryotes
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callose
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A complex polysaccharide, 1,3-glucan, synthesized in the plasma membrane and deposited between the plasma membrane and the cell wall; a common wall constituent in the sieve areas of sieve elements; also develops rapidly in reaction to injury in sieve elements and parenchyma cells
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bordered pit
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A pit in which the secondary wall arches over the pit membrane
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actin filament
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A helical protein filament, 5 to 7 nanometers thick, composed of globular actin molecules; a major constituent of the cytoskeleton of all eukaryotic cells. Also called a microfilament
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basal body
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A self-reproducing, cylinder-shaped cytoplasmic organelle from which cilia or flagella arise; identical in structure to the centriole, which is involved in mitosis and meiosis in most animals and protists
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centriole
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[Gk. kentron, center, + L. -olus, little one] A cytoplasmic organelle found outside the nuclear envelope and identical in structure to a basal body; found in the cells of most eukaryotes other than fungi, red algae, and the nonflagellated cells of plants. Centrioles divide and organize spindle fibers during mitosis and meiosis
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prokaryote
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[Gk. pro, before, + karyon, kernel] A cell lacking a membrane-bounded nucleus and membrane-bounded organelles; Bacteria and Archaea
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vacuole
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[L. vacuus, empty] A space or cavity within the cytoplasm filled with a watery fluid, the cell sap; a lysosomal compartment
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tonoplast
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[Gk. tonos, stretching, tension, + plastos, formed, molded] The cytoplasmic membrane surrounding the vacuole in plant cells. Also called the vacuolar membrane
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plasma membrane or plasmalemma
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Outer boundary of the cytoplasm, next to the cell wall; consists of a single membrane. Also called cell membrane or ectoplasm
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cytosol
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The cytoplasmic matrix of the cytoplasm in which the nucleus, various organelles, and membrane systems are suspended
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protoplast
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The protoplasm of an individual cell; in plants, the unit of protoplasm inside the cell wall
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nucleoid
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A region of DNA in prokaryotic cells, mitochondria, and chloroplasts
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protoplasm
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A general term for the living substance of all cells
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organelle
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[Gk. organella, small tool] A specialized, membrane-bounded part of a cell
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cyclosis
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[Gk. kyklosis, circulation] The streaming of cytoplasm within a cell
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chromoplast
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A plastid containing pigments other than chlorophyll, usually yellow and orange carotenoid pigments
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cristae
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sing. crista Infoldings of the inner mitochondrial membrane that form a series of crests or ridges, containing the electron transport chains involved in ATP formation
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flagellum
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pl. flagella [L. flagellum, whip] A long, threadlike organelle that protrudes from the surface of a cell. Bacterial flagella are capable of rotary motion and consist of a single protein fiber each. Eukaryotic flagella, which are used in locomotion and feeding, consist of an array of microtubules with a characteristic internal 9-plus-2 microtubule structure; they are capable of a vibratory, but not rotary, motion. A cilium is a small eukaryotic flagellum
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endoplasmic reticulum
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A complex, three-dimensional membrane system of indefinite extent present in eukaryotic cells, dividing the cytoplasm into compartments and channels. Those portions that are densely coated with ribosomes are called rough endoplasmic reticulum, and other portions with fewer or no ribosomes are called smooth endoplasmic reticulum
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endomembrane system
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Collectively, the cellular membranes that form a continuum (plasma membrane, tonoplast, endoplasmic reticulum, Golgi bodies, and nuclear envelope)
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chloroplast
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A plastid that contains chlorophylls; the site of photosynthesis. Chloroplasts occur in plants and algae
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chromosome
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[Gk. chroma, color, + soma, body] The structure that carries the genes. Eukaryotic chromosomes are visualized as threads or rods of chromatin, appearing in contracted form during mitosis and meiosis, and otherwise are enclosed in a nucleus; each eukaryotic chromosome contains a linear DNA molecule. Prokaryotes typically have a single chromosome consisting of a circular DNA molecule
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chromatin
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The deeply staining complex of DNA and proteins that forms eukaryotic chromosomes
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expansins
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A novel class of proteins involved in the loosening of cell wall structure
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endoplasmic reticulum
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A complex, three-dimensional membrane system of indefinite extent present in eukaryotic cells, dividing the cytoplasm into compartments and channels. Those portions that are densely coated with ribosomes are called rough endoplasmic reticulum, and other portions with fewer or no ribosomes are called smooth endoplasmic reticulum
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cutin
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[L. cutis, skin] Fatty substance deposited in many plant cell walls and on the outer surface of epidermal cell walls, where it forms a layer known as the cuticle
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endocytosis
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[Gk. endon, within, + kytos, hollow vessel] The uptake of material into cells by means of invagination of the plasma membrane; if solid material is involved, the process is called phagocytosis; if dissolved material is involved, it is called pinocytosis
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cytoskeleton
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The flexible network within cells, composed of microtubules and actin filaments, or microfilaments
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cisterna
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pl. cisternae [L. cistern, reservoir] A flattened or saclike portion of the endoplasmic reticulum or a Golgi body (dictyosome)
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diploid
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Having two sets of chromosomes; the 2n (diploid) chromosome number is characteristic of the sporophyte generation
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vacuole
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[L. vacuus, empty] A space or cavity within the cytoplasm filled with a watery fluid, the cell sap; a lysosomal compartment
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grana
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sing. granum Structures within chloroplasts, seen as green granules with a light microscope and as a series of stacked thylakoids with an electron microscope; contain the chlorophylls and carotenoids and are the sites of the light reactions of photosynthesis
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leucoplast
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[Gk. leuko, white, + plasein, to form] A colorless plastid; leucoplasts are commonly centers of starch formation
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polysome or polyribosome
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An aggregation of ribosomes actively involved in the translation of the same mRNA molecule, one after another
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symbiosis
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[Gk. syn, together with, + bios, life] The living together in close association of two or more dissimilar organisms; includes parasitism (in which the association is harmful to one of the organisms) and mutualism (in which the association is advantageous to both)
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plastid
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Organelle in the cells of certain groups of eukaryotes that is the site of such activities as food manufacture and storage; plastids are bounded by two membranes
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mitochondrion
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pl. mitochondria [Gk. mitos, thread, + chondrion, small grain] A double-membrane-bounded organelle found in eukaryotic cells; contains the enzymes of the citric acid cycle and the electron transport chain; the major source of ATP in nonphotosynthetic cells
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ribosome
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A small particle composed of protein and RNA; the site of protein synthesis
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programmed cell death
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The genetically controlled, or programmed, series of changes in a living cell or organism that lead to its death
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peroxisome
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A spherical, single-membrane-bounded organelle, ranging in diameter from 0.5 to 1.5 micrometers; some peroxisomes are involved in photorespiration, and others (called glyoxysomes) with the conversion of fats to sugars during seed germination. Also called a microbody
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stroma
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[Gk. stroma, anything spread out] The ground substance of plastids
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prolamellar body
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Semicrystalline body found in plastids arrested in development by the absence of light
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proplastid
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A minute, self-reproducing body in the cytoplasm from which a plastid develops
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thylakoid
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[Gk. thylakos, sac, + oides, like] A saclike membranous structure in cyanobacteria and in the chloroplasts of eukaryotic organisms; in chloroplasts, stacks of thylakoids form the grana; chlorophylls are found within the thylakoids
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pit membrane
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The middle lamella and two primary cell walls between two pits
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middle lamella
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The layer of intercellular material, rich in pectic compounds, cementing together the primary walls of adjacent cells
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interphase
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The period between two mitotic or meiotic cycles; the cell grows and its DNA replicates during interphase
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hemicellulose
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A polysaccharide resembling cellulose but more soluble and less ordered; found particularly in cell walls
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pectin
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A highly hydrophilic polysaccharide present in the intercellular layer and primary wall of plant cell walls; the basis of fruit jellies
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nucleolus
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pl. nucleoli [L. nucleolus, small nucleus] A small, spherical body found in the nucleus of eukaryotic cells; composed chiefly of rRNA that is in the process of being transcribed from copies of rRNA genes; the site of production of ribosomal subunits
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microfibril
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A threadlike component of the cell wall, composed of cellulose molecules, visible only with the electron microscope
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lignin
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One of the most important constituents of the secondary wall of vascular plants, although not all secondary walls contain lignin; after cellulose, lignin is the most abundant plant polymer
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pit
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A recessed cavity in a cell wall where a secondary wall does not form
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mitosis
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[Gk. mitos, thread] A process during which the duplicated chromosomes divide longitudinally and the daughter chromosomes then separate to form two genetically identical daughter nuclei; usually accompanied by cytokinesis
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microtubule
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[Gk. mikros, small, + L. tubulus, little pipe] Narrow (about 25 nanometers in diameter), elongated, nonmembranous tubule of indefinite length. Microtubules occur in the cells of eukaryotes; they move the chromosomes in cell division and provide the internal structure of cilia and flagella
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nucleolar organizer region
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A special area on a certain chromosome that is associated with formation of the nucleolus
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Golgi body
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In eukaryotes, a group of flat, disk-shaped sacs that are often branched into tubules at their margins. Also called a dictyosome. Golgi bodies serve as collecting and packaging centers for the cell and are concerned with secretory activities. The term "Golgi apparatus" (or "Golgi complex") refers collectively to all the Golgi bodies, or dictyosomes, of a given cell
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plasmodesma
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pl. plasmodesmata [Gk. plasma, form, + desma, bond]: The minute cytoplasmic threads that extend through openings in cell walls and connect the protoplasts of adjacent living cells
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initial
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A cell that remains within the meristem indefinitely and, at the same time, divides and adds cells to the plant body
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pit-pair
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Two opposite pits plus the pit membrane
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glyoxysome
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A peroxisome containing the enzymes necessary for the conversion of fats into carbohydrates; glyoxysomes play an important role during the germination of seeds
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tonoplast
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[Gk. tonos, stretching, tension, + plastos, formed, molded]: The cytoplasmic membrane surrounding the vacuole in plant cells. Also called the vacuolar membrane
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primary cell wall
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The wall layer deposited during the period of cell expansion
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suberin
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[L. suber, cork oak] Fatty material found in the cell walls of cork tissue and in the Casparian strip of the endodermis
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primary pit-field
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Thin area in a primary cell wall through which plasmodesmata pass, although plasmodesmata may also occur elsewhere in the wall
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secondary cell wall
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Innermost layer of the cell wall, formed in certain cells after cell elongation has ceased; secondary walls have a highly organized microfibrillar structure
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genome
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The totality of genetic information contained in the nucleus, plastid, or mitochondrion
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polyploid
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Referring to an organism, tissue, or cell with more than two complete sets of chromosomes
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haploid
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Gk. haploos, single] Having only one set of chromosomes (n), in contrast to diploid (2n)
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simple pit
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A pit not surrounded by an overarching border of secondary wall; as opposed to a bordered pit
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photorespiration
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The oxygenase activity of Rubisco combined with the salvage pathway, consuming O2 and releasing CO2; occurs when Rubisco binds O2 instead of CO2
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nuclear envelope
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The double membrane surrounding the nucleus of a cell
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anaphase
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[Gk. ana, away, + phasis, form] A stage in mitosis in which the chromatids of each chromosome separate and move to opposite poles; also, similar stages in meiosis in which chromatids or paired chromosomes move apart
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cell plate
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The partition that forms at the equator of the spindle in the dividing cells of plants and a few green algae during early telophase
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entromere
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[Gk. kentron, center, + meros, part] Region of constriction of a chromosome that holds sister chromatids together
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kinetochore
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[Gk. kinetikos, causing motion, + chorus, chorus] Specialized protein complex that develops on each centromere and to which spindle fibers are attached during mitosis or meiosis
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metaphase
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The stage of mitosis or meiosis during which the chromosomes lie in the equatorial plane of the spindle
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mitotic spindle
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The array of microtubules that forms between the opposite poles of a eukaryotic cell during mitosis
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phragmoplast
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A spindle-shaped system of microtubules that arises between two daughter nuclei at telophase and within which the cell plate is formed during cell division, or cytokinesis. Phragmoplasts are found in all green algae except members of the class Chlorophyceae and in all plants
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phragmosome
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The layer of cytoplasm that forms across the cell where the nucleus becomes located and divides
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preprophase band
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A ringlike band of microtubules, lying just beneath the plasma membrane, that delimits the equatorial plane of the future mitotic spindle of a cell preparing to divide
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prophase
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Gk. pro, before, + phasis, form] An early stage in nuclear division, characterized by shortening and thickening of the chromosomes and their movement to the metaphase plate
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