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Cells Unit
4. Exchange with the Environment
Term | Definition |
---|---|
Cell Division | Allows organisms to grow and repair injuries. |
Where does the exchange of materials between a cell and its environment take place? | At the cell membrane. |
diffusion | the movement of particles from regions of higher density to regions of low density. |
osmosis | the diffusion of water through a semipermeable membrane. The concentration of particles in blood is kept in check by osmosis. |
molecules | particles that make up water |
Semipermeable | only certain substances can pass through the membrane |
channels | particles cross cell membranes by way of these |
Passive Transport | the movement of substances across a cell membrane without the use of energy (diffusion and osmosis) |
Active Transport | the movement of substances across a cell membrane that requires the cell to use energy |
small particles move through membranes by | diffusion, passive transport and active transport |
Large particles move through membranes by | endocytosis and exocytosis |
endocytosis | the process by which a cell membrane surrounds a particle and encloses the particle in a vesicle to bring particle in the cell |
vesicles | sacs formed from pieces of cell membrane. |
exocytosis | the process in which a cell releases a particle by enclosing the particle in a vesicle that then moves to the cell surface and fuses with the cell membrane. |