front 1 Diffusion | back 1 The spontaneous movement of a substance down its concentration gradient from where it is more concentrated to where it is less concentrated |
front 2 Passive transport | back 2 The diffusion of a substance across a biological membrane, with no expenditure of energy |
front 3 Osmosis | back 3 The diffusion of water across a selectively permeable membrane |
front 4 Facilitated diffusion | back 4 The passage of substance through a specific transport protein across a biological membrane down to its concentration gradient |
front 5 Active transport | back 5 The movement of a substance across a biological membrane against its concentration gradient, aided by specific transport proteins and requiring an input of energy (often as ATP) |
front 6 Concentration gradient | back 6 A region along which the density of a chemical substance increases or decreases. Cells often maintain concentration gradients of ions across their membranes. When a gradient exists, substances tend to move from where they are more concentrated to where they are less concentrated |
front 7 Hypotonic | back 7 Referring to a solution that, when surrounding a cell, will cause the cell to take up water |
front 8 Hypertonic | back 8 Referring to a solution that, when surrounding a cell, will cause the cell to lose water |
front 9 Isotonic | back 9 Referring to a solution that, when surrounding a cell, has no effect on the passage of water into or out of the cell |
front 10 Aquaporin | back 10 A transport protein in the plasma membrane of some plant or animal cells that facilitates the diffusion of water across the membrane (osmosis) |
front 11 Exocytosis | back 11 The movement of materials out of the cytoplasm of a cell by the fusion of vesicles with the plasma membrane |
front 12 Endocytosis | back 12 Cellular uptake of molecules or particles via formation of new vesicles from the plasma membrane |
front 13 Phagocytosis | back 13 Cellular "eating"; a type of endocytosis in which a cell engulfs macromolecules, other cells, or particles into its cytoplasm |
front 14 Pinocytosis | back 14 Cellular "drinking"; a type of endocytosis in which the cell takes fluid and dissolved solutes into small membraneous vesicles |
front 15 Receptor-mediated endocytosis | back 15 The movement of specific molecules into a cell by the inward budding of membranous vesicles, which contain proteins with receptor sites specific to the molecules being taken in |
front 16 Enzyme | back 16 A macromolecule, usually a protein, that serves as a biological catalyst, changing the rate of a chemical reaction without being consumed bt the reaction |
front 17 Substrate | back 17 (1)A specific substance (reactant) on which an enzyme acts. Each enzyme recognizes substrate or substrates of the reaction it catalyzes (2) A surface in or on which an organism |
front 18 Active site | back 18 The part of an enzyme molecule where a substrate molecule attaches (by means of weak chemical bonds); typically, a pocket or groove on the enzyme's surface. |
front 19 Induced fit | back 19 The change of shape of an active site of an enzyme, caused by the entry of the substrate, so that it binds more snugly to the substrate |
front 20 Cofactor | back 20 A non protein molecule or ion that is required for the proper functioning of an enzyme |
front 21 Coenzyme | back 21 An organic molecule serving as a cofactor. Most vitamins functions as a coenzymes in important metabolic reactions |
front 22 Competitive inhibitor | back 22 A substance that reduces the activity of an enzyme by binding to the enzyme's active site in place of the substrate. A competitive inhibitor's structure mimics that of the enzyme's substrate. |
front 23 Non-competivie inhibitor | back 23 A substance that reduces the activity of an enzyme without entering an active site. By binding elsewhere on the enzyme, a noncompetitive inhibitor changes the shape of the enzyme so that the active site no longer effectively catalyzes the conversion of substrate to product |
front 24 Allosteric site | back 24 A site that allows molecules to either activate or inhibit (or turn off) enzyme activity |
front 25 Kinetic energy | back 25 The energy of motion |
front 26 Potential energy | back 26 The energy that matter possesses because of its location or arrangement. |
front 27 Entropy | back 27 A measure of disorder |
front 28 Exergonic | back 28 An energy-releasing chemical reaction in which the reactants contain more potential energy than the products. |
front 29 Endogonic | back 29 An energy-requiring chemical reaction, which yields more potential energy in the products than the reactants. |
front 30 Aerobic | back 30 A process that requires the presence of oxygen or air as opposed to an anaerobic process that does not require it |
front 31 Anarobic | back 31 Any organism that does not require molecular oxygen for growth |
front 32 1st Law of Thermodynamics | back 32 Energy can neither be created nor destroyed |
front 33 2nd Law of Thermodynamics | back 33 For a spontaneous process, the entropy of the universe increases |