Cell Wall: Type, Structure and Function

The hard non-living covering found outside the protoplasmic membrane of plants is called cell wall.

The bacterial cell wall is made up of proteins, lipids and polysaccharides.  Apart from this, N-acetyl glucosamine acid and N-acetyl muramic acid are found in the cell wall. The cell wall protects the cell from mechanical damage and infection, as well as maintains interactions between cells and provides a barrier to undesirable macromolecules. The cell wall in fungi is made up of chitin or fungal cellulose. The cell wall of algae is made up of cellulose, galactans and minerals like calcium carbonate.

In other plants it is made up of cellulose, hemicellulose, pectin and lignin. The cell wall is a wall-like layer that surrounds the protoplasm. It encloses the protoplasm and acts as a safety cover.


Structure

Now that we have known what is a cell wall, let us have a look about its structure.  On the basis of structure the following types of cell wall are found.

1. Primary wall
2. Secondary wall
3. Tertiary wall
4. Middle Plaque


Primary wall
The primary wall is made up of microfibrils. Microfibrils are initially disordered but gradually become elongated as the cell matures and excess material accumulates.

• Cellulose microfibrils, microscopic fibers are linked to each other by hydrogen bonds with the help of xyloglucan chains. This means that it forms a continuous lattice, which is trapped in the second mesh.

• Pectic Polysaccharide It forms the second network and residues of galactouronic acid are found in large quantities in it. In this, calcium and other ionic bonds form crosslinks.

• Structural protein, the third is the intracellular network. In this web, a web of structural proteins is woven.

Secondary wall
When the primary wall is formed, only then this wall is formed by the deposition of other materials. Microfibrils are arranged parallel to this layer. In a mature cell, only the secondary wall is clearly visible, as its thickness is much greater than that of the primary and tertiary walls.

Tertiary wall
The tertiary wall is formed by irritation which is not found in all cells.

Middle lamella
The middle lamella is the layer connecting two cells. The primary wall is found on both sides of it, which is of two separate cells. It is made of calcium pectate. It is a chemical structure that can be dissolved by strong acids.

Fig : middle lamella

Functions

The main function of the cell wall is to provide strength to the cell. We know that plants do not have any kind of skeletal system. That is why this wall gives strength. The cell wall is made up of the components of a living cell. They provide protection, firmness, shape, etc. to the cell.  But its special thing is that it itself is inanimate.