CELL WALL 6 TH LAB Lecturer: Salma Alrdahe

CELL WALL It is the wall of a cell in plants, bacteria, fungi, algae, and some archaea. Animals and protozoa do not have cell walls. Functions of the cell wall: Cell walls protect the cells from damage. It is also there to make the cell strong, to keep its shape, and to control the growing of the cell and plant. It is outside the cell membrane and gives these cells support and protection, as well as acting as a filter.

S TRUCTURE OF THE CELL WALL Up to three layers may be found in plant cell walls:  The middle lamella, a layer rich in pectins. middle lamella  The primary cell wall, generally a thin and flexible layer formed while the cell is growing. primary cell wall The main chemical components of the primary plant cell wall include cellulose, pectins and cross- linking glycans.

S TRUCTURE OF THE CELL WALL  The secondary cell wall, a thick layer formed inside the primary cell wall after the cell is fully grown. It is not found in all cell types. secondary cell wall It has a composition nearly identical to that of the earlier-developed wall. However, additional substances, especially lignin, are found in the secondary wall.

P LASMODESMATA Plasmodesmata (singular, plasmodesma) are small channels that directly connect the cytoplasm of neighboring plant cells to each other, establishing living bridges between cells. It act as a tunnels to help regulating the transportation of the nutrients and compounds between all the cells using normal passive diffusion and active transport systems.