Plant Cell Wall: Structure, Component, Function

The plant cell wall is a distinctive feature that sets plant cells apart from animal cells. It is a rigid structure that surrounds the plant cell's plasma membrane. The plant cell wall is primarily composed of carbohydrates, including cellulose, hemicellulose, and pectin. Cellulose is the main component and multiple linear chains of cellulose bundled together to form microfibrils. These microfibrils are embedded in a network of other polysaccharides to form the cell wall. The thickness of the cell wall ranges from 0.1 to several micrometers.

The primary cell wall, middle lamella, secondary cell wall, and plasmodesmata.

There is a relatively thin layer called the primary cell wall adjacent to the plasma membrane in young plant cells. It is elastic and can expand its surface area as the cell grows. The primary cell wall is mainly composed of cellulose, but it also contains hemicellulose and pectin. Adjacent cells secrete polysaccharides, primarily pectin, on their contact surfaces. These polysaccharides form a thin layer called the middle lamella which acts like glue to bind the cells together.

As plant cells mature, they develop a secondary cell wall between the primary cell wall and plasma membrane to provide additional strength. The secondary cell wall is thicker and harder than the primary cell wall. It contains not only abundant cellulose but also some lignin. Lignin is a complex polymer with a high content of phenyl groups, and greatly enhances mechanical strength and hardness. Some plants also incorporate substances like suberin, cutin, and minerals into the secondary cell wall.

Adjacent cells are connected by channels called plasmodesmata that traverse the plant cell wall and connect the cytoplasm of neighboring cells. These channels allow communication and molecular transport between cells, facilitating the coordination and exchange of resources.

Function of Plant cell wall

Support and protection: The cell wall's rigid and tough nature allows plants to withstand mechanical stress and maintain upright growth. The cell wall also acts as a physical barrier to protect plant cells from external mechanical damage and pathogen invasion.

Regulation of Water intake: When the vesicle is full of water, the cell wall gives the cytoplasm a resistance to prevent it from taking in too much water, which could lead to cell bursting.

Transport: The plasmodesmata worked as transport pathways for the movement of molecules between adjacent cells, such as nutrients and signaling molecules.

Adhesion: The middle lamella hold the neighboring cells together to form tissues and organs.

Frequently Asked Questions

What is the function of suberin, cutin and minerals?

Suberin: It is a hydrophobic substance and prevents water and air from passing through cell walls. It acts as a barrier against water loss, pathogens, and mechanical damage.

Cutin: It is a transparent hydrophobic film that covers the surface of plants. It often mixes with wax to reduce water loss from the plant's surface and helps prevent mechanical damage, such as abrasion and infection.

Minerals: Minerals such as calcium and silicon accumulate within the cell walls, contributing to increased hardness and protection of tissues.