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77 Cards in this Set

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Endoplasmic reticulum (ER)

Rough
An extensive membranous network in eukaryotic cells, continuous with the outer nuclear membrane and composed of ribosome-studded regions
Endoplasmic Reticulum (ER)

Smooth
An extensive membranous network in eukaryotic cells, continuous with the outer nuclear membrance and ribosome-free regions
Centrosome
Material present in the cytoplasm of all eukaryotic cells, important during cell division; the microtubule-organizing center
Peroxisome
A microbody containing enzymes that transfer hydrogen from various substrates to oxygen, producing and then degrading hydrogen peroxide
Microvillus (microvilli)
One of many fine, fingerlike projections of the epithelial cells in the lumen of the small intestine that increase its surface area
Cytoskeleton
A network of microtubules, microfilaments and intermediate filaments that branch throughout the cytoplasm and serve a variety of mechanical and transport functions
Microfilaments
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
Intermediate Filament
A component of the cytoskeleton that includes all filaments intermediate in size between microtubules and microfilaments
Microtubule
A hollow rod of tubulin protein in the cytoplasm of all eukaryotic cells and in cilia, flagella, and the cytoskeleton
Lysosome
A membrane-enclosed bag of hydrolytic enzymes found in the cytoplasm of eukaryotic cells
Mitochondrion
An organelle in eukaryotic cells that serves as the site of cellular respiration
Golgi Apparatus
An organelle in eukaryotic cells consisting of stacks of flat membranous sacs that modify, store, and route products of the endoplasmic reticulum
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
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
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.
Nucleolus
A specialized structure in the nucleus, formed from various chromosomes and active in the synthesis of ribosomes
Nuclear Envelope
The membrane in eukaryotes that encloses the nucleus, separating it from the cytoplasm
Central Vacuole
A membranous sac in a mature plant cell with diverse roles in reproduction, growth development
Tonoplast
A membrane that encloses the central vacuole in a plant cell, separating the cytosol- from the cell sap
Chloroplast
An organeele found only in plants and photosynthetic protists that absorbs sunlight and uses it to drive the synthesis of organic compounds fromcarbon dioxide and water
Plasmodesmata
An open channel in the cell wall of plants through which strands of cytosol connect from adjacent cells
Cell Wall
A protective layer external to the plasma membrane in plant cells, bacteria, fungi, and some protists. In plant cells, the wall is formed of cellulose fibers embedded in a polysaccharide-protein matrix, The primary cell wall is thin and flexible, whereas the secondary cell wall is stronger and more rigid and is the primary constituent of wood.
Peroxisome
A microbody containing enzymes that transfer hydrogen fromvarious substrates to oxygen, producing and then degrading hydrogen peroxide
Chromatin
The complex of DNA and proteiins that nmakes 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
Nuclear Lamina
A netlike array of protein filaments that maintains the shape of the nucleus
Nucleolus
A specialized structure in the nucleus, formed from various chromosomes and active in the synthesis of ribosomes
Phagocytosis
A type of endocytosis involving large, particulate substances
light microscope
the first microscopes used by Renaissance scientists, use light and lenses to magnify the image of the specimen; light is refracted to magnify the image
resolving power
a measure of the clarity of the image; the minimum distance two points can be separated and still be distinguished as two separate points
electron microscope
a form of microscopy in which a beam of electrons are passed through the specimen
transmission electron microscope (TEM)
used predominantly to study the internal ultrastructure of cells; focus a beam of electrons, using electromagnets, through a small portion of the specimen
scanning electron microscope (SEM)
useful for detailed study of the surface of the specimen; great depth of field results in an image that appears three-dimensional
cell fractionation
to take cells apart, separating the major organelles so that their functions can be studied
ultracentrifuges
powerful centrifuges that can spin the solution at speeds of up to 80,000 revolutions per minute
endomembrane
a system made up of many different membranes that are related either through direct physical continuity or as the transfer of membrane segments as tiny vesicles; includes the nuclear envelope, endoplasmic reticulum, Gogli apparatus, lysosomes, various kinds of vacuoles, and the plasma membrane; thickness, molecular composition, and metabolic behavior of a membrane can change over time
Glycoproteins
proteins that are covalently bonded to carbohydrates
Transport vesicles
vesicles that are in transit from one part of the cell to another that transport cellular products
Food vacuoles
large, membrane bound sacs formed by phagocytosis
Contractile vacuoles
used by many protests, etc. to pump excess water from the cell
Cristae
convoluted infoldings of the inner membrane in a mitochondrion; encloses the mitochondrial matrix; gives the inner membrane a large surface area that enhances productivity of cellular respiration
Centrioles
centrioles are composed of nine sets of triplet molecules; a pair of centrioles is located within the centrosome of an animal cell
Flagella
locomotive appendages that protrude from some cells; usually limited to one or a few per cell
Cilia
locomotive appendages that protrude from some cells; usually occur in large numbers across the cell surface
Basal body
structure that anchors the microtubule assembly within a flagella or cilia in the cell; structurally identical to a centriole
Dynein
a motor molecule (protein) that connects microtubule doublets together in a cilia or flagella; responsible for the beating motion of the cellular extension; undergoes a series of movements caused by changes in the conformation of the protein powered by ATP
Actin
a globular protein which composes microfilaments in the cytoskeleton
Myosin
a protein that is prevalent in muscle cells, functions as a motor molecule, it is found in an alternating pattern with actin; allows the muscle cells to shorten
Pseudopodia
an ameboid cell crawls along a surface by extending and flowing into this cellular extension; composed of actin-myosin fibers; white blood cells in humans move by crawling
Selective permeability
a key feature of plasma membranes;
allows some substances to cross a membrane more easily than others
Amphipathic
contains both water-loving and water-fearing components
Fluid mosaic model
the current model used to describe the structure of membranes;
according to this model, the membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids
Integral proteins
generally transmembrane proteins, with hydrophobic regions (stretches of nonpolar amino acids) that completely span the hydrophobic interior of the membrane
Peripheral proteins
proteins that are not embedded in the lipid bilayer at all;
loosely bound to the surface of the membrane, often to the exposed parts of integral proteins
Transport proteins
integral proteins that selectively transport molecules across the membrane
Diffusion
the tendency for molecules of any substance to spread out into the available space;
a spontaneous process that decreases free energy
Concentration gradient
in the absence of other forces, a substance will diffus efrom where it is more concentrated to where it is less concentrated (down its conc. gradient)
Passive transport
the diffusion of a substance across a biological membrane;
the cell does not have to expend energy to make this happen
Hypertonic
when comparing two solutions of unequal solute concentration, refers to the solution with a higher conc. of solute
Hypotonic
when comparing two solutions of unequal solute concentration, refers to the solution with a lower conc. of solute
Isotonic
describes two solutions that are equal in solute conc.
Osmosis
a spcial case of active transport;
diffusion of water across a selectively permeable membrane
Osmoregulation
the control of water balance
Facilitated diffusion
the spontaneous passage of molecules and ions, bound to specific carrier proteins, across a biological membrane down their conc. gradients
Gated channels
proteins that respond to a stimulus by opening or closing;
stimulus may be electrical or chemical
Active tranpsor
a process by which a cell moves a solute against its conc. gradient by expending its own energy
Sodium-potassium pump
a transport protein which exchanges sodium for potassium across the membrane of animal cells in order to maintain specific conc. of each within the cell;
the main electrogenic pump of animal cells
Membrane potential
the voltage across a membrane;
reflects the separation of charges across a membrane
Electrochemical gradient
the combination of the electrical gradient and the chemical gradient that drive the movement of ions across membranes
Electrogenic pump
a transport protein that generates voltage across a membrane, storing energy in the form of voltage
Proton pump
the main electrogenic pump plant, fungi, and bacteria cells;
actively transports hydrogen ions out of the cell
Cotransport
a mechanism by which a single ATP-powered pump that transports a specific solute can indirectly drive the active transport of several other solutes
Exocytosis
a process by which cells secrete macromolecules by the fusion of vesicles with the plasma membrane
Endocytosis
a process by which cells take in macromolecules and particular matter by forming new vesicles from the plasma membrane
Phagocytosis
a process by which a cell engulfs a particle by wrapping pseudopodia around it and packaging it within a membrane enclosed sac; the sac then combines with a lysosome and the particle is digested
Pinocytosis
a process by which the cell "gulps" droplets of extracellular fluid in tiny vesicles
Receptor-mediated endocytosis
endocytosis that occurs when a specific molecule comes into to contact with specific membrane proteins
Ligands
a general term for any molecule that binds specifically to a receptor site of another molecule;
from the Latin "ligare" which means "to bind"