Term | Definition |
semi-permeable | membranes that allow some substances through but not others |
cell membrane (aka plasma membrane) | A cell structure that controls which substances can enter or leave the cell. |
cytoskeleton | A network of fibers that holds the cell together, helps the cell to keep its shape, and aids in movement |
active transport | The movement of materials through a cell membrane using energy. |
carrier protein | a protein that transports substances across a cell membrane |
concentration gradient | A difference in the concentration of a substance across a distance. |
diffusion | Movement of molecules from an area of higher concentration to an area of lower concentration. |
endocytosis | A process in which a cell engulfs extracellular material through an inward folding of its plasma membrane. |
exocytosis | a process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane. |
osmosis | Diffusion of water through a selectively permeable membrane |
passive transport | The transportation of materials across a plasma membrane without using energy. |
facilitated diffusion | A process in which substances are transported across a plasma membrane with the concentration gradient with the aid of carrier (transport) proteins; does not require the use of energy. |
homeostasis | A tendency to maintain a balanced or constant internal state; the regulation of any aspect of body chemistry, such as blood glucose, around a particular level |
isotonic | Having the same solute concentration as another solution. |
hypertonic | Having a higher concentration of solute than another solution. |
hypotonic | Having a lower concentration of solute than another solution |