Cell Wall (Plant, Fungal, Bacterial)- Structure and Functions


The cell wall is a rigid and protective layer that surrounds the plasma membrane of some cells. It is not a living structure, but it is produced by the living protoplast (the living part of the cell) inside the cell. The cell wall provides mechanical support and shape to the cell, and also serves as a barrier against external threats.

The cell wall is not present in animal cells, but it is found in most plant cells, fungi, bacteria, algae, and some archaea. The cell wall differs in composition and structure depending on the type of organism. For example:

  • In plant cells, the cell wall is mainly composed of cellulose, a polysaccharide made of glucose units. Cellulose forms long and strong fibers that give the cell wall its strength and flexibility. The cell wall also contains other polysaccharides, such as hemicellulose and pectin, and some proteins.
  • In fungi, the cell wall is mainly composed of chitin, a polysaccharide made of N-acetylglucosamine units. Chitin forms rigid and tough fibers that protect the fungal cell from damage. The cell wall also contains other polysaccharides, such as glucans, and some proteins.
  • In bacteria, the cell wall is mainly composed of peptidoglycan, a complex molecule made of sugar chains cross-linked by peptide bonds. Peptidoglycan forms a mesh-like layer that gives the bacterial cell its shape and prevents it from bursting due to osmotic pressure. The cell wall also contains other molecules, such as lipids and proteins.

The cell wall has many important functions in a cell, such as:

  • Providing support and structure to the cell and the whole organism
  • Withstanding turgor pressure (the internal pressure caused by water inside the cell)
  • Regulating cell growth and division
  • Regulating the diffusion of substances into and out of the cell
  • Communicating with other cells through pores or channels
  • Protecting the cell from pathogens, toxins, and environmental stress
  • Storing carbohydrates for energy or growth

The cell wall is a dynamic structure that can change its composition and thickness according to the needs of the cell. For example, some plant cells can form a secondary cell wall inside the primary cell wall to increase their strength and rigidity. Some bacteria can modify their cell wall to resist antibiotics or evade immune system recognition.

The cell wall is one of the most distinctive features of non-animal cells. It plays a vital role in maintaining the integrity and function of the cell and the organism. In this article, we will explore the structure and functions of the cell wall in plants, fungi, and bacteria in more detail.