Animals and protozoa do not have cell walls.Cell walls are found in plants, bacteria, fungi, algae, and some Achaea.Some cells, such as the conductiong cells in xylem, possess a secondary wall containing lignin, which strengthens and waterproofs the cell.
3) The secondary cell wall, a thick layer formed inside the primary cell wall after the cell is fully grown. 2) The primary cell wall, generally a thin, flexible and extensible layer formed while the cell is growing. This outermost layer forms the interface between adjacent plant cells and glues them together. There are several layers in plant cell walls:Ĭell Wall The middle lamella, a layer rich in pectins.It is a barrier between cell and its environment.
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