| Term | Definition |
|---|
| passive transport | the movement of substances across a cell membrane without the use of energy by the cell. |
| diffusion | the movement of particles from regions of higher density to regions of lower density. |
| concentration gradient | a difference in the concentration of a substance across a distance. |
| equilibrium | in biology, a state that exists when the concentration of a substance is the same throughout a space. |
| osmosis | the diffusion of water or another solvent from a more dilute solution (of a solute) to a more concentrated (of the solute) through a membrane that is permeable to the solvent. |
| hypotonic | describes a solution whose solute concentration is lower than the solute concentration inside a cell. |
| hypertonic | describes a solution whose solute concentration is higher than the solute concentration inside a cell. |
| isotonic | describes a solution whose concentration is equal to the solute concentration inside a cell. |
| contractile vacuole | in protists, an organelle that accumulates water and then releases it periodically to maintain osmotic pressure. |
| turgor pressure | the pressure that is exerted on the inside of cell walls and that is caused by the movement of water into the cell. |
| plasmolysis | the contraction or shrinking of the cell membrane of a plant cell in a hypertonic solution in response to the loss of water by osmosis. |
| cytolysis | the bursting of a cell. |
| facilitated diffusion | the transport of substances through a cell membrane along a concentration gradient with the aid of carrier proteins. |
| carrier protein | a protein that transports substances across a cell membrane. |
| ion channel | a complex of protein molecules in a cell membrane that form a pore through which ions can pass. |
| active transport | the movement of chemical substances, usually across the cell membrane, against a concentration gradient; requires cells to use energy. |
| sodium-potassium pump | a carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell. |
| endocytosis | the process by which a cell membranes surrounds a particle and encloses the particle in a vesicle to bring the particle into the cell. |
| vesicle | a small cavity or sac that contains materials in a eukaryotic cell; forms when part of the cell membrane surrounds the materials to be taken into the cell or transported within the cell. |
| pinocytosis | a method of active transport across the cell membrane in which the cell takes in extracellular fluids. |
| phagocytosis | the process by which a cell engulfs large particles or whole cells, either as a defense mechanism or as a means to obtain food. |
| phagocyte | a cell that ingests and destroys (digests) foreign matter or microorganisms. |
| 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. |
Combine with other sets
Share on Facebook
Share on MySpace