The cell wall is known to be a tough, flexible and a fairly rigid layer that surrounds certain types of cells. It is found outside the cell membrane and provide cells with protection and structural support, while also acts as a filtering mechanism. One of the major cell wall functions is to act as a pressure vessel that prevents over expansion as water enters the cell. Cell walls are found in plants, fungi, bacteria, algae and in other archea. Protozoa and animals do not have cell walls and this is one of the major differences between animal and plant cells.

Plant Cell Structure

The cell wall of plants is a very remarkable structure as it gives the major difference between plant cells as well as other eukaryotic cells. It is very rigid, can be many micrometers in thickness, and provides plant cells a much defined shape. Although most cells have an outer membrane, none is comparable to the plant cell wall’s strength. Due to the fact that plants have evolved this rigid structure, they have lost the opportunity to develop immune systems, nervous systems and most importantly, mobility.

Plant Cell Wall Composition

The cell wall is mainly composed of polysaccharides, proteins and cellulose fiber. In new cells, the cell wall is not very rigid and thin, which allows the young cells room to grow and develop. The primary cell wall is the first cell wall of the growing plant cells. Once the cell is fully grown, the primary cell walls are normally retained and are thickened and it will develop the secondary cell walls, which are the deposited new layers of a different material. Every cell wall is interacting with the other cell walls in order to form a tightly bound structure of plants. Despite the cell walls’ rigidity, cellular excretions and chemical signals are allowed to pass between cells.

Non-Plant Cell Function

The algal cell walls not only contain glycoproteins and cellulose but also include forms of polysaccharides that are not found in plants such as carrageenan and agarose. Diatom algae contain silicon in the form of silicic acid in their cell walls. The cell wall function of bacteria is often  for protection against the human immune system and other environmental hazards. The primary components of cell walls, known as peptidoglycan, is the substance detected for in gram staining. Similar antibiotics such as penicillin target the bacterial cell wall.

©2005-2015 Plant Biology Advice - Dean Ravenscroft