For a cell, if water moves out of the cell into the surrounding solution, the solution is said to be hypertonic - the concentration of dissolved material is more in the solution than in the cell. In such a solution the cell will contract. The structures and properties of the biomolecules on which life depends, proteins, nucleic acids, lipids and complex carbohydrates, are entirely dependent on the unique properties of water and no other solvent has properties similar to water. The noncovalent interactions between biomolecules, which are essential for the proper functioning of biomolecules, depend entirely on the properties of water. It is this very weakness which holds the key to their importance, because it means that noncovalent interactions are continually being formed and broken in the dynamic processes that characterize life.
Noncovalent interactions involve electrical charges.
These electrical interactions can be direct, as in ionic or dipole interactions. They can be indirect, as in induced dipole or dispersion forces , in which distortion of the electrons in nonpolar molecules is the basis for the interaction. The Hydrogen bond is also a noncovalent interaction. Water has a high dielectric constant, which means that ionic interactions in water are much weaker than in other solvents. This is due to the fact water solvates ions through charge-dipole interactions.