The cell wall encloses all plant cells.It is made of cellulose.Cellulose is a polymer of beta-glucose. Long molecules of cellulose are bound together to form strong fibres. The fibres form a mat glued together by pectin and hemicelluloses.The cell wall is freely permeable to water and small molecules. When the cell is full of water, it becomes turgid. The cell contents press against the cell wall making it rigid.This supports the cell and the plant as a whole.The cell wall also acts as a defence mechanisms against the entry of pathogens.