Structural Function - Essential Elements
The elements nitrogen, phosphorus and sulphur absorbed from the soil are essential components of amino acids and nucleotides. The other two elements that are constituents of important compounds are Mg2+ and ca2+. While Mg2+ is part of chlorophyll molecule and ca2+ is an integral part of the middle lamella and is thought to be essential for maintaining structural characteristic of cell walls. It also maintains the permeability of plasma membrane.
In its absence cells begin to leak out. In recent years a new regulatory role that ca2+ plays in the cell is beginning to be appreciated. It plays the role of a second messenger.