Cell wall

Cell wall is a structural layer surrounding some types of cells, situated outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mechanism. Cell walls are present in most prokaryotes, in algae, fungi and eukaryotes including plants but are absent in animal cells.

Structure and Composition

The cell wall is composed of polysaccharides such as cellulose, and hemicellulose, glycoproteins and phenolic compounds such as lignin. The materials in the cell wall vary between species and can help determine the cell's pathogenicity.

Function

The primary function of the cell wall is to provide support and protection for the cell. It acts as a pressure vessel, preventing over-expansion when water enters the cell. They are also involved in directing cell growth, preventing cell rupture, maintaining cell shape, and are involved in a number of other functions as well.

Evolution

The evolution of the cell wall can be traced back to the first prokaryotic organisms. The development of the cell wall has been a key factor in allowing organisms to live in a variety of different environments.

See also

• Cell membrane
• Prokaryote
• Eukaryote
• Plant cell