Atomic and molecular composition of the cell.

Cells are made up of water, inorganic ions, and carbon-containing (organic) molecules. Water is the most abundant molecule in cells, accounting for 70% or more of the total mass of cells. Consequently, the interaction between water and other cell components is of central importance in biological chemistry. The critical property of water in this regard is that it is a polar molecule in which hydrogen atoms have a slight positive charge and oxygen has a slight negative charge.