The cell wall is the non-living and outermost covering of a cell consisting of cellulose and is permeable. It helps in separating the contents of the cell from the environment. It provides shape and protection to the cells and is present only in plant cells and absent in the animal cell.Prokaryotes usually contain large polymers and are known as peptidoglycans. These molecules then give strength to the bacteria cell wall. There are some prokaryotic cell wall which are having two layers –
- An inner layer that is made up of peptidoglycans
- An outer layer that is composed of lipoproteins and lipopolysaccharides
- Eukaryotic cells possess a definite nucleus along with a distinct nuclear membrane. The living structure of a cell is known as cell organelles.
In Eukaryotes, the cell has 3 main parts:
- Primary Cell Wall
- The Middle Lamella
- The Secondary cell Wall
The Primary cell wall is situated closest to the inside of the cell and is the first formed cell wall. It is mainly made up of cellulose, allowing the wall to stretch as the cell starts to grow. Several primary cells contain pectic polysaccharides and structural proteins. It is heard that the outermost layer of the cell which is comparatively permeable and thin.
The Middle Lamella consists of lignin, pectins and some proteins. The cells of the plant tissues are combined together with the middle lamella.
The Secondary cell wall consists of both the cellulose and a lignin as the strong material. Lignin helps in strengthening the wall and provides a rectangular shape to a cell. It is thick and permeable.
Cell Wall Functions
- The plant cell wall provides definite shape, strength, rigidity, and protection against mechanical stress.
- Helps in controlling cell expansion.
- It helps in preventing water loss from the cell.
- Involved in transporting of substances between and across the cell.
- It acts as a barrier between the cell interior and the outer environment.