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| A channel protein in the plasma membrane of a plant, animal, or microorganism cell that specifically facilitates osmosis, the diffusion of free water across the membrane. |
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| A region along which the density of a chemical substance increases or decreases. |
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| The coupling of the “downhill” diffusion of one substance to the “uphill” transport of another against its own concentration gradient. |
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| The spontaneous movement of a substance down its concentration or electrochemical gradient, from a region where it is more concentrated to a region where it is less concentrated. |
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| The diffusion gradient of an ion, which is affected by both the concentration difference of an ion across a membrane (a chemical force) and the ion's tendency to move relative to the membrane potential (an electrical force). |
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| An active transport protein that generates voltage across a membrane while pumping ions. |
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| Cellular uptake of biological molecules and particulate matter via formation of vesicles from the plasma membrane. |
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| The cellular secretion of biological molecules by the fusion of vesicles containing them with the plasma membrane. |
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| -Limp..) Lacking turgor (stiffness or firmness), as in a plant cell in surroundings where there is a tendency for water to leave the cell. (A walled cell becomes flaccid if it has a higher water potential than its surroundings, resulting in the loss of water. |
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| A protein with one or more covalently attached carbohydrates. |
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| Referring to a solution that, when surrounding a cell, will cause the cell to lose water. |
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| Referring to a solution that, when surrounding a cell, will cause the cell to take up water. |
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| A transmembrane protein channel that allows a specific ion to diffuse across the membrane down its concentration or electrochemical gradient. |
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| The difference in electrical charge (voltage) across a cell's plasma membrane due to the differential distribution of ions. Membrane potential affects the activity of excitable cells and the transmembrane movement of all charged substances. |
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| Regulation of solute concentrations and water balance by a cell or organism. |
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| A phenomenon in walled cells in which the cytoplasm shrivels and the plasma membrane pulls away from the cell wall; occurs when the cell loses water to a hypertonic environment. |
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| A property of biological membranes that allows them to regulate the passage of substances across them. |
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| A transport protein in the plasma membrane of animal cells that actively transports sodium out of the cell and potassium into the cell. |
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| Swollen or distended, as in plant cells. (A walled cell becomes turgid if it has a lower water potential than its surroundings, resulting in entry of water.) |
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| dual (amphipathic molecule: a molecule that has both a hydrophobic and a hydrophilic region) |
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| a small opening (aquaporin: a transport protein in the plasma membrane of a plant or animal cell that specifically facilitates the diffusion of water across the membrane) |
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| across (cotransport: the coupling of the "downhill" diffusion of one substance to the "uphill" transport of another against its own concentration gradient) |
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| producing (electrogenic pump: an ion transport protein generating voltage across a membrane) |
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| cell (endocytosis: the movement of materials into a cell; cell eating) |
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| outer (exocytosis: the movement of materials out of a cell) |
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| tension (hypertonic: a solution with a higher concentration of solutes) |
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| lower (hypotonic: a solution with a lower concentration of solutes) |
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| same (isotonic: solutions with equal concentrations of solutes) |
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| eat (phagocytosis: cell eating) |
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| drink (pinocytosis: cell drinking) |
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| = loosen (plasmolysis: a phenomenon in walled cells in which the cytoplasm shrivels and the plasma membrane pulls away from the cell wall when the cell loses water to a hypertonic environment) |
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