Across
- 3. A transmembrane protein channel that allows a specific ion to diffuse across the membrane down its concentration or electrochemical gradient.
- 4. The movement of a substance across a cell membrane against its concentration or electrochemical gradient, mediated by specific transport proteins and requiring an expenditure of energy.
- 8. Referring to a solution that, when surrounding a cell, will cause the cell to lose water.
- 9. The passage of molecules or ions down their electrochemical gradient across a biological membrane with the assistance of specific transmembrane transport proteins, requiring no energy expenditure.
- 10. Referring to a solution that, when surrounding a cell, causes no net movement of water into or out of the cell.
Down
- 1. Referring to a solution that, when surrounding a cell, will cause the cell to take up water.
- 2. The diffusion gradient of an ion, which is affected by both the concentration difference of an ion across a membrane (a chemical force) and the ion's tendency to move relative to the membrane potential (an electrical force).
- 5. A channel protein in a cellular membrane that specifically facilitates osmosis, the diffusion of free water across the membrane.
- 6. The random thermal motion of particles of liquids, gases, or solids. In the presence of a concentration or electrochemical gradient, diffusion results in the net movement of a substance from a region where it is more concentrated to a region where it is less concentrated.
- 7. A transmembrane protein with hydrophobic regions that extend into and often completely span the hydrophobic interior of the membrane and with hydrophilic regions in contact with the aqueous solution on one or both sides of the membrane (or lining the channel in the case of a channel protein).