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57 Cards in this Set
- Front
- Back
activation energy |
the amount of energy that reactants must absorb before a chemical reaction will start |
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active site |
the part of an enzyme where a substrate molecule attaches; typically, a pocket or groove in the enzymes side |
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active transport |
the movement of a substance across a biological membrane against its concentration gradient, aided by specific transport proteins and requiring input energy (often as ATP) |
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aquaporin |
a transport protein in the plasma membrane of an animal, plant, or microorganism cell that facilitates the diffusion of water across the membrane (osmosis) |
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ATP |
adenosine triphosphate, the main energy source for cells. ATP releases energy when its phosphate bongs are hydrolyzed |
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cellular respiration |
the aerobic harvesting of energy from food molecules; the energy-releasing chemical breakdown of food molecules, such as glucose, and the storage of potential energy in a form the cell can use to perform work; involves glycosis, the citric acid cylce, and oxidative phosphorylation (the electron transport chain) |
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chemical energy |
energy available in molecules for release in a chemical reaction; a form of potential energy |
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coenzyme |
an organic molecule serving as a cofactor. most vitamins function as these. |
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cofactor |
a nonprotein molecule or ion that is required for the proper functioning of an enzyme |
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competitive inhibitor |
a substance that reduces the activity of an enzyme by entering the active site in place of the substrate. structure mimics an enzyme's substrate's structure |
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concentration gradient |
a region along which the density of a chemical substances increases or decreases; cells often maintain these of ions across their membranes; when it exists, substances tend to move from where they are more concentrated to where there are less of these |
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diffusion |
the random movement in particles that results in the net movement of a substance down its concentration gradient from a region where it is more concentrated to where it is less so |
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endergonic reaction |
an energy-requiring chemical reaction, which yields products with more potential energy than the reactants |
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endocytosis |
cellular uptake of molecules or particles via formation of new vesicles from the plasma membrane |
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energy |
the capacity to cause change, especially to perform work |
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energy coupling |
in cellular metabolism, the use of energy release from an exergonic reaction to drive an endergonic reaction |
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entropy |
a measure of disorder, or randomness. |
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enzyme |
a protein that acts a catalyst to speed up a chemical reaction by lowering the activation energy |
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exergonic reaction |
an energy-releasing chemical reaction in which the reactants contain more potential energy than the products |
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exocytosis |
the movement of materials out of a cell by the fusion of vesicles with the plasma membrane |
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facilitated diffusion |
the passage of a substance through a specific transport protein across a biological membrane down its concentration gradient |
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feedback inhibition |
a method of metabolic control in which a product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway |
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first law of thermodynamics |
the principle of conservation of energy; energy can be transferred and transformed, but it cannot be created or destroyed |
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fluid mosaic model |
the currently accepted model of cell membrane structure, depicting the membrane as a mosaic of diverse molecules embedded in a fluid bilayer of phospholipid molecules |
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heat |
thermal energy in transfer from one body of matter to another |
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hypertonic |
referring to a solution that, when surrounding a cell, will cause a cell to lose water |
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hypotonic |
referring to a solution that, when surrounding a cell, will cause the cell to take up water |
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isotonic |
referring to a solution that, when surrounding a cell, cause no net movement of water into or out of the cell |
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kinetic energy |
the energy associate with the motion of objects. moving matter does work by imparting motion to other matter |
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metabolic pathway |
a series of chemical reactions that either builds a complex molecule or breaks down a complex molecule into simpler compounds |
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metabolism |
the totality of an organism's chemical reactions |
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noncompetitive inhibitor |
a substance that reduces the activity of an enzyme without entering an active site. by binding elsewhere on the enzyme, it changes the shape of the enzyme so that the active site no longer effectively catalyzes the conversion of substrate to product |
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osmoregulation |
the homeostatic maintenance of solute concentrations and water balance by a cell or organism |
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osmosis |
the diffusion of free water across a selectively permeable membrane |
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passive transport |
the diffusion of a substance across a biological membrane with no expenditure of energy |
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phagocytosis |
cellular "eating"; a type of endocytosis in which a cell ungulfs macromolecules, other cells, or particles in its cytoplasm |
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phosphorylation |
the transfer of a phosphate group, usually from ATP, to a molecule. nearly all cellular work depends on ATP energizing other molecules this way. |
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potential energy |
the energy that matter possesses because of its location or spatial arrangement. (water behind a dam) |
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receptor-mediated endocytosis |
the movement of specific molecules into a cell by the infolding of vesicles containing proteins with receptor sites specific to the molecules being taken in |
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second law of thermodynamics |
the principle stating the every energy confersion reduces the order of the universe, increasing its entropy. ordered forms of energy are at least partly converted to heat. |
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substrate |
a specific substance (reactant) on which an enzyme acts. each enzyme recognizes only the specific one or the one that it catalyzes |
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thermal energy |
kinetic energy due to the random motion of atoms and molecules; energy in its most random form |
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thermodynamics |
the study of energy transformation that occurs in a collection of matter |
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tonicity |
the ability of a solution surrounding a cell to cause that cell to gain or lose water |
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aqua- |
water |
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-pori |
a small opening |
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co- |
together |
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endo- |
inner; within |
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exo- |
outer |
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hyper- |
exceeding |
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-tonus |
tension |
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hypo- |
lower |
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iso- |
same |
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kinet- |
movement |
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osmo- |
pushing |
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phago- |
eat |
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therm- |
heat |