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| transmembrane protein that helps a certain substance or class of closely related substances to cross the membrane | ||
| transport protein in the plasma membrane of a plant or animal cell that specifically facilitates the diffusion of water across the membrane (osmosis) | ||
| increase or decrease in density of chemical substance in an area; cells often maintain this of ions across membranes; ions or other chemical substances involved tend to move from where they are more concentrated to where they are less concentrated | ||
| the diffusion of a substance across a biological membrane | ||
| the spontaneous tendency of a substance to move down its concentration gradient from a more concentrated to a less concentrated area | ||
| the diffusion of water across a selectively permeable membrane | ||
| the abilit of a solution to cause a cell within it to gain or lose water | ||
| having the same solute concentration as another solution | ||
| in comparing two solutions, referring to the one with a greater solute concentration | ||
| in comparing two solutions, referring to the one with a lower solute concentration | ||
| how organisms regulate solute concentrations and balance the gain and loss of water | ||
| very firm; a walled cell becomes turgid if it has a greater solute concentration than its surroundings, resulting in entry of water | ||
| limp; a walled cell is flaccid in surroundings where there is no tendency for water to enter | ||
| a phenomenon in walled cells in which the cytoplasm shrivels and the plasma membrane pulls away form the cell wall when the cell loses water to a hypertonic environment | ||
| the spontaneous passage of molecules and ions, bound to specific carrier proteins, across a biological membrane down their concentration gradients | ||
| protein channels in a cell membrane that allow passage of a specific ion down its concentration gradient | ||
| a protein channel in a cell membrane that opens or closes in response to a particular stimulus | ||
| the movement of a substance across a biological | ||
| a special transport protein in the plasma membrane of animal cells that transports sodium out of the cell and potassium into the cell against their concentration gradients | ||
| charge difference between a cell's cytoplasm and the extracellular fluid, due to differential distribution of ions; affects activity of excitable cells and transmembrane movement of all charged substances | ||
| diffusion gradient of ion, representing type of potential energy that allows for both the concentration difference of ions across membrane and its tendency to move relative to membrane potential | ||
| ion transport protein that generates voltage across membrane | ||
| active transport mechanism in cell membranes that uses ATP to force hydrogen ions out of a cell, generating membrane potential in process -- makes solution more acidic | ||
| type of endocytosis involving large, particulate substances, accomplished mainly by macrophages, neutrophils, and dendritic cells | ||
| type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes | ||
| cellular uptake of macromolecules and particulate substances by localized regions of plasma membrane that surround the substance and pinch off to form intracellular vesicle | ||
| cellular secretion of macromolecules by the fusion of vesicles with the plasma membrane | ||
| amphipathic molecules (has both hydrophilic region and hydrophobic region); fluidity; movement | ||
| unsaturated hydrocarbon tails of phospholipids have kinks that keep the molecules from packing together, enhancing, membrane fluidity | ||
| lateral movement of phospholipids within membrane is rapid; flip-flopping is rare | ||
| steroid wedged between phospholipid molecules in plasma membranes of animal cells | ||
| reduces membrane fluidity at moderate temperatures by reducing phospholipid movements, but at low temperatures it hinders solidification by disrupting the regular packing of phospholipids | ||
| penetrate the hydrophobic core of lipid bilayer; functions include transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular junction | ||
| protein that spans membrane may provide pydrophilic channel across membrane that is selective for particular solute; other ones shuttle substances by changing shape (hydrolyze ATP as energy source) | ||
| protein built into membrane may be enzyme with active site exposed to substances in adjacent solution; sometimes several organized as team | ||
| membrane protein may have binding site with specific shpae that fits the shape of chemical messenger; external messenger may cause conformational change in protein that relays the message to inside of the cell | ||
| some glycoproteins serve as identification tages that are specifially recognized by other cells | ||
| membrane proteins of adjacent cells may hook together in various kinds of junctions | ||
| not embedded in bilayer; appendages loosely bound to surface of membrane | ||
| microfilaments of other cytoskeleton elements may be bonded to membrane proteins, helps maintain cell shape and stabilizes location of membrane proteins; proteins that adhere to ECM can coordinate extracellular and intracellular changes | ||
| carbohydrates covalently bonded to lipids; function as markers that distinguish one cell from another | ||
| carbohydrates covalently bonded to proteins; functiona as markers that distinguish one cell from another |
