Cell Wall Structure

Cell Wall Structure

• The cell wall consists of three fundamental parts: middle lamella, primary wall, and secondary wall.

Middle Lamella

• The middle lamella cements together the walls of neighboring cells.
• It is usually thin, about 1μm in thickness.
• In woody tissues, the middle lamella is commonly lignified.

Primary Wall

• The primary wall is the first wall formed in a developing cell.
• It is usually 1-3μm in thickness.
• It is more or less elastic and extendable, crystalline, and optically active.
• The primary wall is composed of cellulose, pectic compounds (mostly polysaccharides), and hemicellulose.

Secondary Wall

• The secondary wall develops after the primary wall.
• It is laid down inside the primary wall.
• The secondary wall is about 5-10μm in thickness, more or less rigid, crystalline, and strongly optically active.
• It is mainly composed of lignin, cellulose, non-cellulosic polysaccharides, hemicelluloses, and mineral salts of Ca, Mg, K, and some silica.

Cell Wall Function

• The cell wall forms a framework for the cell to prevent over-expansion.
• Cellulose fibers, structural proteins, and other polysaccharides help maintain the shape and form of the cell.

This quiz covers the three fundamental parts of cell walls, including middle lamella, primary wall, and secondary wall. Learn about their composition, thickness, and properties.