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bio 3.3-3.5 terms
Term | Definition |
---|---|
cell membrane | double layer of phospholipids that forms a boundary between a cell and the surrounding environment; controls what passes in and out of a cell |
phospholipid | a lipid that contains phosphorus; a structural component in the cell membranes |
fluid mosaic model | model that describes the arrangement and movement of molecules that make up a cell membrane |
selective permability | condition of allowing some, not all, materials to cross the membrane and enter the cell |
receptor | protein that detects a signal molecule and performs an action in response |
passive transport | the movement of substances across a cell membrane without the use of energy by the cell |
diffusion | the movement of particles from areas of higher density to areas of lower density |
consentration gradient | the difference in the concentration of a substance across a distance |
osmosis | the diffusion of water or another solvent from a more dilute solution (of a solute) to a more concentrated solution (of a solute) through a membrane that is permeable to the solvent |
isotonic | solution that has equal cocentration of dissolved particles compared with another solution |
hypertonic | describes a solution whose solute concentration is higher than the solute concentration inside the cell |
hypotonic | describes a solution whose solute concentration is lower than the solute concentration inside a cell |
facilitated diffusion | the transport of substances through a cell membrane along a concentration gradient with the aid of carrier proteins |
active transport | the movement of chamical substances, usually across the cell membrane, against a concentration gradient; requires a cell to use energy |
endocytosis | the process by which a cell membrane surrounds a particle in a vesicle to bring the particle into the cell |
phagocytosis | uptake a solid particle into a cell by engulfing the particle |
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 |