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6.5.4. Cell wall functions

Cell wall functions

The main functions of the cell wall are:

  • Constitute the cellular exoskeleton that gives protection to the cell, gives it shape and gives it resistance , but allows its growth.
  • Allow the plant to stand upright.
  • It acts as a barrier against some pathogens.
  • It intervenes in the maintenance of intracellular osmotic pressure, preventing the cell from breaking.

Plant cells normally live in a hypotonic environment (with less concentration of solutes than their interior), which causes water to enter their interior by osmosis . When the hydrostatic pressure is already too high, the cell wall prevents more water from entering. This pressure, called turgor , is vital for the plant and causes movements in the plants, such as the opening and closing of stomata , leaves and flowers that move when touched, etc.

The cell wall of adult cells can undergo changes in its chemical composition depending on the function they perform.

In conductive or support tissues, the wall increases its rigidity, but without losing its permeability. They can have two types of modifications:

  • Lignification: lignin is deposited, as in the cells of the conducting vessels of the xylem.
  • Mineralization: impregnation of calcium carbonate, CaCO3, or silica, SiO2 , as occurs in epidermal cells.

If the function of the cell is to waterproof it, cutin (a fatty acid polymer, which makes fruits and leaves shine) or suberin (forms the cork) is deposited on the surface of the epidermal cells.