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Campbell Biology: Ninth Edition - Chapter 6: A Tour of the Cell

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light microscope (LM)
an optical instrument with lenses that refract (bend) visible light to magnify images of specimens
organelle
any of several membrane-enclosed structures with specialized functions, suspended in the cytosol of eukaryotic cells
electron microscope (EM)
a microscope that uses magnets to focus an electron beam on or through a spectrum, resulting in a practical resolution of a hundredfold greater than that of a light microscope using standard techniques. A transmission electron microscope (TEM) is used to study the internal structure of thin sections of cells. A scanning electron microscope (SEM) is used to study the fine details of the cell surface.
scanning electron microscope (SEM)
a microscope that uses an electron beam to scan the surface of the sample, coated with metal atoms, to study details of its topography.
transmission electron microscope (TEM)
a microscope that passes electron beam through very thin sections stained with metal atoms and is primarily used to study the internal ultrastructure of cells
cell fractionation
the disruption of a cell and separation of its parts by centrifugation at successively higher speeds
cytosol
the contents of the cell bounded by the plasma membrane; in eukaryotes, the portion exclusive of the nucleus
eukaryotic cell
a type of cell with membrane-enclosed nucleus and membrane-enclosed organelles. Organisms with eukaryotic cells (protists, fungi, and animals) are called eukaryotes
prokaryotic cell
a type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles. Organsims with prokaryotic cells (bacteria and archaea) are called prokaryotic.
nucleoid
a non-membrane-bounded region in a prokaryotic cell where the DNA is concentrated
cytoplasm
the contents of the cell bounded by the plasma membrane; in eukaryotes, the portion exclusive of the nucleus
plasma membrane
the membrane at the boundary of every cell that acts as a selective barrier, regulating the cell's chemical composition
nucleus
an atom's central core, containing protons and neutrons; the organelle of a eukaryotic cell that contains the genetic material in the form of chromosomes, made up of chromatin; a cluster of neutrons
nuclear envelope
in a eukaryotic cell, the double membrane that surrounds the nucleus, perforated with pores that regulate traffic with the cytoplasm. The outer membrane is continuous with the endoplasmic reticulum
nuclear lamina
a netlike array of protein filaments that lines the inner surface of the nuclear envelope and helps maintain the shape of the nucleus
chromosome
a cellular structure carrying genetic material, found in the nucleus of eukaryotic cells. Each chromosome consists of one very long DNA molecule and associated proteins (a bacterial chromosome usually consists of a single circular DNA molecule and associated proteins. It is found in the nucleoid region, which is not membrane bounded.
chromatin
the complex of DNA and proteins that makes up eukaryotic chromosomes. When the cell is not dividing, chromatin exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope
nucleolus
a specialized structure in the nucleus, consisting of chromosomal regions containing ribosomal RNA (rRNA) genes along with ribosomal proteins imported from the cytoplasm; site of rRNA synthesis and ribosomal subunit assembly
ribosome
a complex of rRNA and protein molecules that function as a site of protein synthesis in the cytoplasm; consists of a large and small subunit. In eukaryotic cells, each subunit is assembled in the nucleolus
endomembrane system
the collection of membranes inside and surrounding a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles; includes the plasma membrane, the nuclear envelope, the smooth and rough endoplasmic reticulum, the Golgi apparatus, lysosomes, vesicles, and vacuoles
vesicle
a membranous sac in the cytoplasm of a eukaryotic cell
endoplasmic reticulum (ER)
an extensive membranous network in eukaryotic cells, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions
smooth ER
the portion of the ER that is free of ribosomes
rough ER
the portion of the ER with ribosomes attached
glycoprotein
a protein with one or more covalently attached carbohydrates
transport vesicle
a small membranous sac in a eukaryotic cell's cytoplasm carrying molecules produced by the cell
Golgi apparatus
an organelle in eukaryotic cells consisting of stacks of flat membranous sacs that modify, store, and route products of the ER and synthesize some products, notably noncellular carbohydrates
lysosome
a membrane-enclosed sac of hydrolytic enzymes found in the cytoplasm of animal cells and some protists.
phagocytosis
a type of endocytosis in which large particulate substances or small organisms are taken up by a cell. It's carried out by some protists and by certain immune cells of animals (in mammals, mainly macrophages, neutrophilis, and dendritic cells).
vacuole
a membrane-bounded vesicle whose specialized function varies in different kinds of cells
food vacuole
a membranous sac fromed by phagocytosis of microorganisms or particles to be used as food by the cell
contractile vacuole
a membranous sac formed that helps moves excess water out of certain freshwater protists
central vacuole
in a mature plant cell, a large membranous sac with diverse roles in growth, storage, and sequestration of toxic substances
mitochondria
an organelle in eukaryotic cells that serves as the site of cellular respiration; uses oxygen to break down organic molecules and synthesize ATP
chloroplast
an organelle found in plants and photosynthetic protists that absorbs sunlight and uses it to drive the synthesis of organic compounds from carbon dioxide
endosymbiont theory
the theory that mitochondria and plastids, including chloroplasts, originated as prokaryotic cells engulfed by an ancestral eukaryotic cell. The engulfed cell and its host cell then evolved into a single organism
cristae
an infolding of the inner membrane of a mitochondrion. The inner membrane houses electron transport chains and molecules of the enzyme catalyzing the synthesis of ATP (ATP synthase)
mitochondrial matrix
the compartment of the mitochondrion enclosed by the inner membrane and containing enzymes and substrates for the citric acid cycle, as well as ribosomes and DNA
thylakoid
a flattened, membranous sac inside a chloroplast. Often exist in stacks called grana that are interconnected; their membranes contain molecular "machinery" used to convert light energy to chemical energy
granum
a stack of membrane-bounded thylakoids in the chloroplast. Grana function in the light reactions of photosynthesis
stroma
the dense fluid within the chloroplast surrounding the thylakoid membrane and containing ribosomes and DNA; involved in the synthesis of organic molecules from carbon dioxide and water
plastid
one of a family of closely related organelles that includes chloroplasts, chromoplasts, and amlyoplasts. Found in cells of photosynthetic eukaryotes
peroxisome
an organelle containing enzymes that transfer hydrogen atoms from various substrates to oxygen (O2), producing and then degrading hydrogen peroxide (H2O2)
cytoskeleton
a network of microtubules, microfilaments, and intermediate filaments that extend throughout the cytoplasm and serve a variety of mechanical, transport, and signaling function.
motor protein
a protein that interacts with cytoskeletal elements and other cell components, producing movement of the whole cell or parts of the cell
microtubules
a hollow rod composed of tubulin proteins that makes up part of the cytoskeleton in all eukaryotic cells and is found in cilia and flagella
centrosome
a structure present in the cytoplasm of animal cells that functions as a microtubule-organizing center and is important during cell division; has 2 centrioles
centriole
a structure in the centrosome of an animal cell composed of a cylinder of microtubule triplets arranged in a 9+0 pattern
flagella
a long cellular appendage apecialized for locomotion. Like motile cilia, eukaryotic flagella have a core with 9 outer doublet microtubules and 2 inner single mictrotubules (the "9+2" arrangement) ensheathed in an extension of the plasma membrane.
cilia
a short appendage containing microtubules in eukaryotic cells. A motile cillium is specialized for locomotion or moving fluid past the cell; formed from a core of 9 outer doublet microtubules and 2 inner single microtubules (the "9+2" arrangement) ensheathed in an ectension of the plasma membrane. Primary cillium usually nonmotile and plays sensory and signaling role; lack 2 inner microtubules (the "9+0" structure)
basal body
a eukaryotic cell structure consisting of a "9+0" arrangement of microtubule triplets. The basal body may organize the microtubule assembly of a cilium or flagellum and is structurally very similar to a centriole
dynein
in cilia and flagella, a large motor protein extending from 1 microtubule doublet to the adjacent doublet. ATP hydrolysis drives changes in its shape that lead to bending of cilia and flagella
microfilament
a cable composed of actin proteins in the cytoplasm of almost every eukaryotic cell, making up part of the cytoskelton and acting alone or with myosin to cause cell contraction; aka actin filament
actin
a globular protein that links into chains, 2 of which twist helically about each other, forming microfilaments (actin filaments) in muscle and other kinds of cells
cortex
outer region of cytoplasm in a eukaryotic cell, lying just under the plasma membrane, that has a more gel-like consistency that the inner regions due to the presence of multiple microfilaments; in plants, ground tissue that is between the vascular tissue and the dermal tissue in a root or eudicot stem
myosin
a type of motor protein that associates into filaments that interact with actin filaments to cause cell contraction
pseudopodia
a cellular extension of amoeboid cells used in moving and feeding
cytoplasmic streaming
a circular flow of cytoplasm, involving interactions of myosin and actin filaments, that speeds the distribution of materials within cells
intermediate filament
a component of the cytoskeleton that includes filaments intermediate in size between microtubules and microfilaments
cell wall
a protective layer external to the plasma membrane in the cells of plants, prokaryotes, fungi and some protists. Polysaccharides such as cellulose (in plants and some protists), chitin (in fungi), and peptidoglycan (in bacteria) are important structural components of them
primary cell wall
the level of protein structure referring to the specific linear sequence of amino acids
middle lamella
in plants, a thin layer of adhesive extracellular material, primarily pectins, found between the primary walls of adjacent young cells
secondary cell wall
regions of repetitive coiling of folding of the polypeptide backbone of a protein due to hydrogen bonding between constituents of the backbone (not the side chains)
extracellular matrix (ECM)
the meshwork surrounding animal cells, consisting of glycoproteins, polysaccharides and proteoglycans synthesized and secreted by the cells
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
proteoglycan
a large molecule consisting of a small core protein with many carbohydrate chains attached, found in the extracellular matrix of animal cells' may consist of up to 95% carbohydrate
fibronectin
in an angiosperm, the stalk portion of the stamen, the pollen-producing reproductive organ of a flower
integrin
in animal cells, a transmembrane receptor protein with 2 subunits that interconnects the extracellular matrix and the cytoskelteton
plasmodesmata
an open channel through the cell wall that connects the cytoplasm of adjacent plant cells, allowing water, small solutes, and some larger molecules to pass between the cells
tight junction
a type of intercellular junction between animal cells that prevents the leakage of material through the space between cells
desmosomes
a type of intercellular junction in animal cells that functions as a rivet, fastening cells together
gap junction
a type of intercellular connection in animal cells, consisting of proteins surrounding a pore that allows the passage of materials between cells