Class 11 Biology Cell : The Unit of Life Cell wall

Cell wall

  • Cell wall is the non-living rigid outer covering for the plasma membrane.
  • Cell wall gives shape to the cell, protects the cell from mechanical damage and infection, helps in cell-to-cell interaction and provides barrier to undesirable macromolecules.
  • Algae have cell wall, made of cellulose, galactans, mannans and minerals like calcium carbonate, while in other plants it consists of cellulose, hemicellulose, pectins and proteins.
  • Primary wall is the cell wall of a young plant cell, which is capable of growth and gradually diminishes as the cell matures and the secondary wall is formed on the inner side of the cell.
  • The middle lamella is a layer mainly of calcium pectate which holds or glues the different neighbouring cells together.
  • The cell wall and middle lamellae may be traversed by plasmodesmata which connect the cytoplasm of neighbouring cells.


Fig. Cell wall

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