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84 Cards in this Set
- Front
- Back
chromosome |
a structure that consists of DNA and associated proteins; carries part or all of the cell's genetic information
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chromatin
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collective term for DNA molecules together with their associated proteins
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endomembrane system
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series of interacting organelles (endoplasmic reticulum, Golgi bodies, vesicles) between nucleus and plasma membrane; produces lipids, proteins. |
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endoplasmic reticulum
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organelle that is a continuous system of sacs and tubes; extension of the nuclear envelope. Smooth ER makes lipids and breaks down carbohydrates and fatty acids; rough ER modifies polypeptides made by ribosomes on its surface.
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vesicles
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small, membrane-enclosed, saclike organelle; different kinds store, transport, or degrade their contents
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peroxisomes
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enzyme-filled vesicle that breaks down amino acids, fatty acids, and toxic substance
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lysosomes
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enzyme-filled vesicle that functions in intracellular digestion
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vacuoles
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a fluid-filled organelle that isolates or disposes of waste, debris, or toxic materials
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central vacuole
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fluid-filled vesicle in many plant cells
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golgi body
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organelle that modifies polypeptides and lipids; also sorts and packages the finished products into vesicles |
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mitochondria
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organelle that produces ATP by aerobic respiration in eukaryotes
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plastids
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category of double-membrane organelle in plants and algal cells. Different types specialize in storage or photosynthesis; e.g., chloroplast, amlyoplast
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chloroplasts
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organelle of photosynthesis in the cells of plants and many protists |
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cytoskeleton
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dynamic framework of protein filaments that support, organize, and move eukaryotic cells and their internal structure
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microtubules |
cytoskeletal element involved in cellular movement; hollow filament of tubulin subunits |
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microfilaments |
reinforcing cytoskeletal element; a fiber of actin subunits |
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cell cortex |
reinforcing mesh of cytoskeletal elements under a plasma membrane |
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intermediate filaments |
stable cytoskeletal element that structurally supports cells and tissues |
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motor proteins |
type of energy using protein that interacts with cytoskeletal elements to move the cell's parts or whole cell |
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cilium |
short, movable structure that projects from the plasma membrane of some eukaryotic cells |
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centriole |
barrel-shaped organelle from which microtubules grow |
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basal body |
organelle that develops from a centriole |
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pseudopods |
a temporary protrusion that helps some eukaryotic cells move and engulf prey |
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extracellular matrix (ECM) |
complex mixture of cell secretions; supports cells and tissues; has roles in cell signaling |
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primary wall |
the first cell wall of young plant cells |
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secondary wall |
lignin-reinforced wall that forms inside the primary wall of a plant cell |
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lignin |
material that stiffens cell walls of vascular plants |
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cuticle |
secreted covering at a body surface |
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cell junctions |
structure that connects a cell to another cell or to extracellular matrix |
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plasmodesmata |
cell junctions that connect the cytoplasm of adjacent plant cells |
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tight junctions |
arrays of fibrous proteins; join epithelial cells and collectively prevent fluids from leaking between them |
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adhering junctions |
cell junction composed of adhesion proteins; anchors cells to each other and extracellular matrix |
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gap junctions |
cell junction that forms a channel across the plasma membrane of adjoining animal cells |
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energy |
the capacity to do work |
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kinetic energy |
the energy of motion |
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first law of thermodynamics |
energy cannot be created or destroyed |
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second law of thermodynamics |
energy tends to disperse spontaneously |
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entropy |
measure of how much the energy of a system is dispersed |
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potential energy |
stored energy |
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reactants |
a molecule that enters a reaction |
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products |
a molecule that remains at the end of a reaction |
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endergonic |
describes a reaction that requires a net input of free energy to proceed (energy in) |
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exergonic |
describes a reaction that ends with a net release of free energy (energy out) |
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activation energy |
minimum amount of energy required to start a reaction |
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catalysis |
the acceleration of a reaction by a molecule that is unchanged by participating in the reaction |
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substrates |
a molecule that is specifically acted upon by an enzyme |
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active sites |
of an enzyme, pocket in which substrates bind and a reaction occurs |
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transition state |
point during a reaction at which substrate bonds reach their breaking point and the reaction will run spontaneously |
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induced-fit model |
the concept that substrate binding to an active sit of an enzyme improves the fit between the two molecules |
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metabolic pathway |
series of enzyme-mediated reactions by which cells build, remodel, or break down an organic molecule |
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feedback inhibition |
mechanism in which a change that results from some activity decreases or stops the activity |
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allosteric |
describes a region of an enzyme that can bind a regulatory molecule and is not the active site |
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redox reaction (oxidation reduction reactions) |
oxidation reduction reaction, in which one molecule accepts electrons (it becomes reduced) from another molecule (which becomes oxidized) |
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electron transfer chain |
array of enzymes and other molecules that accept and give up electrons in sequence, thus releasing the energy of the electrons in usable increments |
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anabolic pathways |
these pathways build molecules |
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catabolic pathways |
these pathways break molecules |
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cyclic pathway |
these pathways regenerate a molecule from the first step |
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antioxidant
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substance that prevents oxidation of other molecules
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cofactor
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a metal ion or a coenzyme that associates with an enzyme and is necessary for its function
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coenzyme
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an organic molecule that is a cofactor
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phosphorylation
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transfer of a phosphate group from one molecule to another
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ATP
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the nucleotide adenosine triphosphate
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ATD/ADP cycle
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process by which cells regenerate ATP. ADP forms when ATP loses a phosphate group, then ATP forms again as ADP gains a phosphate group
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fluid mosaic
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model of a cell membrane as a two dimensional fluid of mixed composition
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adhesion proteins
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membrane protein that helps cells stick together in animal tissues
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recognition proteins
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plasma membrane protein that identifies a cell as belonging to self (one's own body)
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receptor protein
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plasma membrane protein that binds to a particular substance outside of the cell
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transport proteins
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protein that passively or actively assists specific ions or molecules accross a membrane
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diffusion
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spontaneous spreading of molecules or ions in a liquid or gas
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concentration
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number of molecules or ions per unit volume
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concentration gradient
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difference in concentration between adjoining regions of fluid
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hypotonic
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describes a fluid that has low overall solute concentration relative to another fluid
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hypertonic
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describes a fluid that has a high overall solute concentration relative to another fluid
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isotonic
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describes two fluids with identical solute concentrations
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osmosis
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the diffusion of water accross a selectivity permeable membrane in response to a concentration gradient
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turgor
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pressure that a fluid exerts against a wall, membrane, or other structure that contains it
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osmotic pressure
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amount of turgor that prevents osmosis into cytoplasm or other hypertonic fluid
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passive transport
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mechanism by which a concentration gradient drives the movement of a solute accross a cell membrane through a transport protein. Requires no energy input.
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active transport
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energy-requiring mechanism in which a transport protein pumps a solute accross a cell membrane against its concentration gradient
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calcium pump
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active transport protein; pumps calcium ions accross a cell membrane against their concentration gradient
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exocytosis
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process by which a cell expels a vesicle's contents to extracellular fluid
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endocytosis
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process by which a cell takes in a small amount of extracellular fluid by ballooning inward of its plasma membrane
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phagocytosis
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"cell eating"; an endocytic pathway by which a cell engulfs particles such as microbes or other cellular debris
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pinocytosis
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endocytosis of bulk materials
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