Term
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Definition
| Any of several membrane-enclosed structures with specialized functions, suspended in the cytosol of eukaryotic cells. |
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Term
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Definition
| The disruption of a cell and separation of its parts by centrifugation |
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Term
prokaryotic cell
(prō′-kār′-ē-ot′-ik) |
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Definition
| A type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles. |
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Term
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Definition
| A dense region of DNA in a prokaryotic cell. |
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Term
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Definition
| The contents of the cell, exclusive of the nucleus and bounded by the plasma membrane. |
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Term
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Definition
| The semifluid portion of the cytoplasm. |
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Term
eukaryotic cell
(yū′-ker-ē-ot′-ik) |
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Definition
| A type of cell with a membrane-enclosed nucleus and membrane-enclosed organelles. |
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Term
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Definition
| The membrane at the boundary of every cell that acts as a selective barrier, regulating the cell’s chemical composition. |
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Term
Chromosome
(krō′-muh-sōm) |
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Definition
| A cellular structure carrying genetic material, found in the nucleus of eukaryotic cells. |
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Term
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Definition
| The complex of DNA and proteins that makes up a eukaryotic chromosome. |
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Term
Nucleolus
(nū-klē′-ō-lus) |
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Definition
| A specialized structure in the nucleus, consisting of chromatin regions containing ribosomal RNA genes along with ribosomal proteins imported from the cytoplasmic site of rRNA synthesis and ribosomal subunit assembly. |
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Term
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Definition
| (1)An atom’s central core, containing protons and neutrons. (2) The chromosome-containing organelle of a eukaryotic cell. (3) A cluster of neurons. |
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Term
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Definition
| The double membrane in a eukaryotic cell that encloses the nucleus, separating it from the cytoplasm. |
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Term
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Definition
| A complex of rRNA and protein molecules that functions as a site of protein synthesis in the cytoplasm; consists of a large and a small subunit. In eukaryotic cells, each subunit is assembled in the nucleolus. |
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Term
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Definition
| A netlike array of protein filaments lining the inner surface of the nuclear envelope; it helps maintain the shape of the nucleus. |
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Term
endoplasmic reticulum (ER)
(en′-dō-plaz′-mik ruh-tik′-yū-lum) |
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Definition
| An extensive membranous network in eukaryotic cells, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions. |
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Term
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Definition
| That portion of the endoplasmic reticulum that is free of ribosomes. |
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Term
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Definition
| That portion of the endoplasmic reticulum studded with ribosomes. |
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Term
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Definition
| The collection of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles; includes the smooth and rough endoplasmic reticulum, the Golgi apparatus, lysosomes, and vacuoles. |
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Term
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Definition
| A sac made of membrane in the cytoplasm. |
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Term
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Definition
| A protein with one or more carbohydrates covalently attached to it. |
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Term
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Definition
| A tiny membranous sac in a cell’s cytoplasm carrying molecules produced by the cell. |
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Term
Golgi apparatus
(gol′-jē) |
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Definition
| An organelle in eukaryotic cells consisting of stacks of flat membranous sacs that modify, store, and route products of the endoplasmic reticulum and synthesize some products, notably noncellulose carbohydrates. |
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Term
Phagocytosis
(fag′-ō-sī-tō′-sis) |
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Definition
| A type of endocytosis in which large particulate substances are taken up by a cell. It is carried out by some protists and by certain immune cells of animals (in mammals, mainly macrophages, neutrophils, and dendritic cells). |
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Term
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Definition
| A membrane-enclosed sac of hydrolytic enzymes found in the cytoplasm of animal cells and some protists. |
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Term
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Definition
| A membranous sac formed by phagocytosis of microorganisms or particles to be used as food by the cell. |
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Term
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Definition
| A membranous sac that helps move excess water out of certain freshwater protists. |
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Term
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Definition
| A membranous sac in a mature plant cell with diverse roles in reproduction, growth, and development. |
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Term
Mitochondrion
(mī′-tō-kon′-drē-un) (plural, mitochondria) |
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Definition
| An organelle in eukaryotic cells that serves as the site of cellular respiration. |
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Term
Chloroplast
(klōr′-ō-plast) |
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Definition
| An organelle found in plants and photosynthetic protists that absorbs sunlight and uses it to drive the synthesis of organic compounds from carbon dioxide and water. |
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Term
Peroxisome
(puh-rok′-suh-sōm′) |
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Definition
| An organelle containing enzymes that transfer hydrogen (H2) from various substrates to oxygen (O2), producing and then degrading hydrogen peroxide (H2O2). |
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Term
Crista
(plural, cristae) (kris′-tuh, kris′-tē) |
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Definition
| An infolding of the inner membrane of a mitochondrion that houses electron transport chains and molecules of the enzyme catalyzing the synthesis of ATP (ATP synthase). |
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Term
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Definition
| The compartment of the mitochondrion enclosed by the inner membrane and containing enzymes and substrates for the citric acid cycle. |
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Term
Thylakoid
(thī′-luh-koyd) |
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Definition
| A flattened membranous sac inside a chloroplast which exist in an interconnected system in the chloroplast and contain the molecular “machinery” used to convert light energy to chemical energy. |
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Term
Granum
(gran′-um) (plural, grana) |
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Definition
| A stack of membrane-bounded thylakoids in the chloroplast which function in the light reactions of photosynthesis. |
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Term
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Definition
| Within the chloroplast, the dense fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide and water. |
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Term
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Definition
| The compartment of the mitochondrion enclosed by the inner membrane and containing enzymes and substrates for the citric acid cycle. |
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Term
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Definition
| One of a family of closely related organelles that includes chloroplasts, chromoplasts, and amyloplasts (leucoplasts), which are found in cells of photosynthetic organisms. |
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Term
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Definition
| A network of microtubules, microfilaments, and intermediate filaments that branch throughout the cytoplasm and serve a variety of mechanical, transport, and signaling functions. |
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Term
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Definition
| A protein that interacts with cytoskeletal elements and other cell components, producing movement of the whole cell or parts of the cell. |
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Term
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Definition
| A hollow rod composed of tubulin proteins that make up part of the cytoskeleton in all eukaryotic cells and is found in cilia and flagella. |
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Term
Centrosome
(sen′-trō-sōm) |
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Definition
| Structure present in the cytoplasm of animal cells, important during cell division; functions as a microtubule-organizing center. |
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Term
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Definition
| A structure in the centrosome of an animal cell composed of a cylinder of microtubule triplets arranged in a 9 + 0 pattern. |
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Term
Flagellum
(fluh-jel′-um) (plural, flagella) |
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Definition
| A long cellular appendage specialized for locomotion. |
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Term
Cilium
(sil′-ē-um) (plural, cilia) |
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Definition
| A short cellular appendage containing microtubules. |
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Term
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Definition
| A eukaryotic cell structure consisting of a 9 + 0 arrangement of microtubule triplets. |
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Term
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Definition
| In cilia and flagella, a large contractile protein extending from one microtubule doublet to the adjacent doublet. |
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Term
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Definition
| A cable composed of actin proteins in the cytoplasm of almost every eukaryotic cell, making up part of the cytoskeleton and acting alone or with myosin to cause cell contraction; also known as an actin filament. |
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Term
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Definition
| A globular protein that links into chains, two of which twist helically about each other, forming microfilaments in muscle and other kinds of cells. |
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Term
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Definition
| (1)The outer region of cytoplasm in a eukaryotic cell, lying just under the plasma membrane, that has a more gel-like consistency than the inner regions, due to the presence of multiple microfilaments. (2) In plants, ground tissue that is between the vascular tissue and dermal tissue in a root or eudicot stem. |
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Term
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Definition
| A type of protein filament that acts as a motor protein with actin filaments to cause cell contraction. |
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Term
Pseudopodium
(sū′-dō-pō′-dē-um) (plural, pseudopodia) |
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Definition
| A cellular extension of amoeboid cells used in moving and feeding. |
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Term
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Definition
| A circular flow of cytoplasm, involving myosin and actin filaments, that speeds the distribution of materials within cells. |
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Term
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Definition
| A component of the cytoskeleton that includes filaments intermediate in size between microtubules and microfilaments. |
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Term
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Definition
| A protective layer external to the plasma membrane in the cells of plants, prokaryotes, fungi, and some protists. |
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Term
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Definition
| In plants, a relatively thin and flexible layer first secreted by a young cell. |
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Term
middle lamella
(luh-mel′-uh) |
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Definition
| In plants, a thin layer of adhesive extracellular material, primarily pectins, found between the primary walls of adjacent young cells. |
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Term
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Definition
| In plants, a strong and durable matrix often deposited in several laminated layers for cell protection and support. |
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Term
| extracellular matrix (ECM) |
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Definition
| The substance in which animal cells are embedded, consisting of protein and polysaccharides synthesized and secreted by cells. |
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Term
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Definition
| A glycoprotein in the extracellular matrix of animal cells that forms strong fibers, found extensively in connective tissue and bone; the most abundant protein in the animal kingdom. |
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Term
Proteoglycan
(prō′-tē-ō-glī′-kan) |
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Definition
| A glycoprotein consisting of a small core protein with many carbohydrate chains attached, found in the extracellular matrix of animal cells. |
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Term
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Definition
| A glycoprotein that helps animal cells attach to the extracellular matrix. |
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Term
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Definition
| In animal cells, a transmembrane receptor protein that interconnects the extracellular matrix and the cytoskeleton. |
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Term
Plasmodesma
(plaz′-mō-dez′-muh) (plural, plasmodesmata) |
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Definition
| An open channel in the cell wall of a plant through which strands of cytosol connect from an adjacent cell. |
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