Chapter 7 Membrane Structure and Function
Order by
38 terms
Terms | Definitions |
|---|---|
 active transport | transport of a substance (as a protein or drug) across a cell membrane against the concentration gradient |
| amphipathic molecule | A molecule that has both a hydrophilic region and a hydrophobic region. |
| aquaporin | A transport protein in the plasma membrane of a plant or animal cell that specifically facilitates the diffusion of water across the membrane (osmosis). |
| bulk transport | The process by which large particles and macromolecules are transported through plasma membranes. Inc. exocytosis and endocytosis |
| carrier transport | proteins carry solutes across cell membrane; specificity: solute binds to a specific receptor site on carrier protein, differs from membrane enzymes because solutes are unchanged; types of carrier mediated transport, facilitated diffusion and active transport |
| concentration gradient | a difference in the concentration of a substance across a distance |
| cotransport | The coupling of the "downhill" diffusion of one substance to the "uphill" transport of another against its own concentration gradient. |
| diffusion | the act of dispersing or diffusing something |
| electrochemical gradient | The diffusion gradient of an ion, representing a type of potential energy that accounts for both the concentration difference of the ion across a membrane and its tendency to move relative to the membrane potential. |
| electrogenic pump | An ion transport protein that generates voltage across a membrane. |
| endocytosis | process by which a cell takes material into the cell by infolding of the cell membrane |
| exocytosis | the process by which a substance is released from the cell through a vesicle that transports the substance to the cell surface and then fuses with the membrane to let the substance out |
| facilitated diffusion | movement of specific molecules passively across cell membranes through protein channels |
| flaccid | lacking firmness or stiffness |
| fluid mosaic model | The currently accepted model of cell membrane structure, which envisions the membrane as a mosaic of individually inserted protein molecules drifting laterally in a fluid bilayer of phospholipids. |
| gated channel | A protein channel in a cell membrane that opens or closes in response to a particular stimulus. |
| glycolipid | A lipid covalently attached to a carbohydrate. |
| glycoprotein | A protein with one or more carbohydrates covalently attached to it. |
| hypertonic | higher concentration of solute and less free water |
| hypotonic | lower concentration of solute and more free water |
| integral protein | A protein imbedded in the bilayer of the cell membrane |
| ion channel | Protein channel in a cell membrane that allows passage of a specific ion down its concentration gradient. |
| isotonic | when the concentration of two solutions is the same |
| ligand | of or involving muscular contraction in which tension is constant while length changes |
| membrane potential | The charge difference between a cell's cytoplasm and the extracellular fluid, due to the differential distribution of ions. Membrane potential affects the activity of excitable cells and the transmembrane movement of all charged substances. |
| osmoregulation | the control of water balance in a cell |
| osmosis | diffusion of molecules through a semipermeable membrane from a place of higher concentration to a place of lower concentration until the concentration on both sides is equal |
| passive transport | transport of a substance across a cell membrane, along its concentration gradient, by diffusion without the use of energy |
| peripheral protein | a protein appendage loosely bound to the surface of a membrane and not embedded in the lipid bilayer |
| phagocytosis | process in which phagocytes engulf and digest microorganisms and cellular debris |
| plasmolysis | when a cell is in a hypertonic environment, the cell will lose water to its surroundings, shrink, and its plasma membrane will pull away from the wall |
| proton pump | An active transport mechanism in cell membranes that uses ATP to force hydrogen ions out of a cell, generating a membrane potential in the process. |
| receptor-mediated endocytosis | The movement of specific molecules into a cell by the inward budding of membranous vesicles containing proteins with receptor sites specific to the molecules being taken in; enables a cell to acquire bulk quantities of specific substances. |
| selective permeability | A property of biological membranes that allows some substances to cross more easily than others. |
| sodium potassium pump | a carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell |
| tonicity | The ability of a solution to cause a cell within it to gain or lose water. |
| transport protein | A transmembrane protein that helps a certain substance or class of closely related substances to cross the membrane. |
| turgid | swollen |
First Time Here?
Welcome to Quizlet, a fun, free place to study. Try these flashcards, find others to study, or make your own.