AP Biology Campbell 7e Ch6
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72 terms
Terms | Definitions |
|---|---|
 actin | A globular protein that links into chains, two of which twist helically about each other, forming microfilaments in muscle and other contractile elements in cells. |
| basal body | A eukaryotic cell organelle consisting of a 9 + 0 arrangement of microtubule triplets; may organize the microtubule assembly of a cilium or flagellum; structurally identical to a centriole. |
| cell fractionation | The disruption of a cell and separation of its organelles by centrifugation. |
| cell wall | A protective layer external to the plasma membrane in plant cells, bacteria, fungi, and some protists. In plant cells, it is formed of cellulose fibers embedded in a polysaccharide-protein matrix. The primary ___ is thin and flexible, whereas the secondary ___ is stronger and more rigid and is the primary constituent of wood. |
| central vacuole | A membranous sac in a mature plant cell with diverse roles in reproduction, growth, and development. |
| centriole | A structure in an animal cell composed of cylinders of microtubule triplets arranged in a 9 + 0 pattern. An animal cell usually has a pair involved in cell division. |
| centrosome | Material present in the cytoplasm of all eukaryotic cells, important during cell division; the microtubule-organizing center. |
| chloroplast | An organelle found only in plants and photosynthetic protists that absorbs sunlight and uses it to drive the synthesis of organic compounds from carbon dioxide and water. |
| chromatin | The complex of DNA and proteins that makes up a eukaryotic chromosome. When the cell is not dividing, chromatin exists as a mass of very long, thin fibers that are not visible with a light microscope. |
| chromosome | A threadlike, gene-carrying structure found in the nucleus. Each chromosome consists of one very long DNA molecule and associated proteins. |
| cilium | A short cellular appendage specialized for locomotion, formed from a core of nine outer doublet microtubules and two inner single microtubules ensheathed in an extension of plasma membrane. |
| collagen | 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. |
| contractile vacuole | A membranous sac that helps move excess water out of the cell. |
| cytoplasm | The entire contents of the cell, exclusive of the nucleus, and bounded by the plasma membrane. |
| cytoplasmic streaming | A circular flow of cytoplasm, involving myosin and actin filaments, that speeds the distribution of materials within cells. |
| cytoskeleton | A network of microtubules, microfilaments, and intermediate filaments that branch throughout the cytoplasm and serve a variety of mechanical and transport functions. |
| cytosol | The semifluid portion of the cytoplasm. |
| desmosome | A type of intercellular junction in animal cells that functions as an anchor. |
| dynein | A large contractile protein forming the side-arms of microtubule doublets in cilia and flagella. |
| electron microscope (EM) | A microscope that focuses an electron beam through a specimen, resolving power a thousandfold greater than that of a light microscope. A transmission ___ is used to study the internal structure of thin sections of cells. A scanning ___ is used to study the fine details of cell surfaces. |
| endomembrane system | The collection of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles. |
| endoplasmic reticulum (ER) | An extensive membranous network in eukaryotic cells, continuous with the outer nuclear membrane and composed of ribosome-studded and ribosome-free regions. |
| eukaryotic cell | A type of cell with a membrane-enclosed nucleus and membrane-enclosed organelles, present in protists, plants, fungi, and animals; also called eukaryote. |
| extracellular matrix (ECM) | The substance in which animal tissue cells are embedded consisting of protein and polysaccharides. |
| fibronectin | A glycoprotein that helps cells attach to the extracellular matrix. |
| flagellum | A long cellular appendage specialized for locomotion, formed from a core of nine outer doublet microtubules and two inner single microtubules, covered in an extension of plasma membrane. |
| food vacuole | A membranous sac formed by phagocytosis. |
| gap junction | A type of intercellular junction in animal cells that allows the passage of material or current between cells; also known as a communicating junction. |
| glycoprotein | A protein covalently attached to a carbohydrate. |
| Golgi apparatus | An organelle in eukaryotic cells consisting of stacks of flat membranous sacs that modify, store, and route products of the endoplasmic reticulum. |
| granum | A stacked portion of the thylakoid membrane in the chloroplast. function in the light reactions of photosynthesis. |
| integrin | Receptor proteins built into the plasma membrane that interconnect the extracellular matrix and the cytoskeleton. |
| intermediate filament | A component of the cytoskeleton that includes all filaments sized between microtubules and microfilaments. |
| light microscope (LM) | An optical instrument with lenses that refract (bend) visible light to magnify images of specimens. |
| lysosome | A membrane-enclosed bag of hydrolytic enzymes found in the cytoplasm of eukaryotic cells. |
| microfilament | A solid rod of actin protein in the cytoplasm of almost all eukaryotic cells, making up part of the cytoskeleton and acting alone or with myosin to cause cell contraction. |
| microtubule | A hollow rod of tubulin protein in the cytoplasm of all eukaryotic cells and in cilia, flagella, and the cytoskeleton. |
| microvillus | One of many fine, fingerlike projections of the epithelial cells in the lumen of the small intestine that increase its surface area. |
| middle lamella | A thin layer of adhesive extracellular material, primarily pectins, found between the primary walls of adjacent young plant cells. |
| mitochondrial matrix | The compartment of the mitochondrion enclosed by the inner membrane and containing enzymes and substrates for the Krebs cycle. |
| mitochondrion | An organelle in eukaryotic cells that serves as the site of cellular respiration. |
| motor protein | Proteins that grip the cytoskeleton to cause cell motility (cell location or parts within the cell). Bk |
| myosin | A type of protein filament that interacts with actin to cause cell contraction. |
| nuclear envelope | The membrane in eukaryotes that encloses the nucleus, separating it from the cytoplasm. |
| nuclear lamina | A netlike array of protein filaments that maintains the shape of the nucleus. |
| nucleoid | A dense region of DNA in a prokaryotic cell. |
| nucleolus | A specialized structure in the nucleus, formed from various chromosomes and active in the synthesis of ribosomes. |
| nucleus | (1) An atom's central core, containing protons and neutrons. (2) The chromosome-containing organelle of a eukaryotic cell. (3) A cluster of neurons. |
| organelle | One of several formed bodies with specialized functions, suspended in the cytoplasm of eukaryotic cells. |
| peroxisome | A microbody containing enzymes that transfer hydrogen from various substrates to oxygen, producing and then degrading hydrogen peroxide. |
| phagocytosis | A type of endocytosis involving large, particulate substances. |
| plasma membrane | The membrane at the boundary of every cell that acts as a selective barrier, thereby regulating the cell's chemical composition. |
| plasmodesma | An open channel in the cell wall of plants through which strands of cytosol connect from adjacent cells. |
| plastid | One of a family of closely related plant organelles, including chloroplasts, chromoplasts, and amyloplasts (leucoplasts). |
| primary cell wall | A relatively thin and flexible layer first secreted by a young plant cell. |
| prokaryotic cell | A type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles; found only in the domains Bacteria and Archaea. |
| proteoglycan | A glycoprotein in the extracellular matrix of animal cells, rich in carbohydrate. |
| pseudopodium | A cellular extension of amoeboid cells used in moving and feeding. |
| ribosome | A cell organelle constructed in the nucleolus and functioning as the site of protein synthesis in the cytoplasm; consists of rRNA and protein molecules, which make up two subunits. |
| rough ER | That portion of the endoplasmic reticulum studded with ribosomes. |
| scanning electron microscope (SEM) | A microscope that uses an electron beam to scan the surface of a sample to study details of its topography. |
| secondary cell wall | A strong and durable matrix often deposited in several laminated layers for plant cell protection and support. |
| smooth ER | That portion of the endoplasmic reticulum that is free of ribosomes. |
| stroma | The fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide and water. |
| thylakoid | A flattened membrane sac inside the chloroplast, used to convert light energy to chemical energy. |
| tight junction | A type of intercellular junction in animal cells that prevents the leakage of material between cells. |
| tonoplast | A membrane that encloses the central vacuole in a plant cell, separating the cytosol from the cell sap. |
| transmission electron microscope (TEM) | A microscope that passes an electron beam through very thin sections, primarily used to study the internal ultrastructure of cells. |
| transport vesicle | A tiny membranous sac in a cell's cytoplasm carrying molecules produced by the cell. |
| ultracentrifuge | A machine that spins test tubes at the fastest speeds to separate liquids and particles of different densities. |
| vacuole | A membrane-enclosed sac taking up most of the interior of a mature plant cell and containing a variety of substances important in plant reproduction, growth, and development. |
| vesicle | A sac made of membrane inside of cells. |
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