The cell wall is a rigid layer of polysaccharides that is located outside of the plasma membrane of the cells of plants, fungi, and bacteria.
In algae and higher plants, it consists mainly of cellulose. In fungi, cell walls are made of the glucosamine polymer chitin. Algae typically have cell walls made of glycoproteins and polysaccharides. |
One of the major functions of the cell wall is to act as a pressure vessel that prevents the over expansion of the cell when water enters it.
It also acts with the cell membrane as a filtering mechanism. It is freely permeable and allows the passage of small molecules and small proteins. |
The cell wall has up to three layers: the middle lamella, the primary cell wall, and the secondary cell wall.
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The cell wall works the most closely with the plamodesta in apoplastic transport, which is transport through the layer outside the plasma membrane, called the apoplast, to move gases like carbon dioxide or plant hormones and pheremones.
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