The cell waw is a very tough, flexible an sometimes fairly rigid layer that surroonds some teeps o cells. It surroonds the cell membrane an provides these cells wi structural support an pertection. In addeetion, the cell waw acts as a filterin mechanism. A major function o the cell waw is to act as a pressur vessel, preventin ower-expansion when watter enters the cell. Cell waws are foond in plants, fungi an prokaryotic cells but nae in mycoplasmas.