Cell Wall

It is the outer semirigid and non-Living boundary of a plant cell.

Chemical Composition:

In its chemical composition cellulose is the most prominent substance, where, the cell wall of fungi is made up of chitin.

Structure:

Thickness of a cell wall varies in different cells e.g. plants; xylem, vessel elements and tracheids have thick walls while parenchyma cells have thin walls.

The primary layer of the cell wall is called primary wall, which is further strengthened by an additional layer called secondary wall, especially in xylem vessels. It is comparatively thicker than primary wall. The cell walls of neighbouring cells are connected by cytoplasmic bridges which are called Plasmodesmata. Through these connections, cells transfer chemicals among each other.

Function:

•          i.            Shape & rigidity: Cell wall provides a definite shape to the cell and keeps it rigid.
•        ii.            Permeable:It does not act as a barrier to the materials passing through it.
•       iii.            Support & Strength: Cell wall provides mechanical strength and skeletal support for the individual cell and to the plant as a whole.
•      iv.            Movement of water & minerals: Water and minerals can move through an interconnected system of cell wall (i.e. the apoplast).
•        v.            Protection:Cell wall protects the cells from osmotic lysis.