What is the cell wall made out of?
The composition of cell walls varies between species and depend on the type of cell and it's developmental stage.
Cell wall is a structural layer, situated outside the cell membrane. Cell walls are present in plants ,fungi and prokaryotic cells.
In bacteria cell walls are composed of peptidoglycans.
Fungi have cell walls formed of chitin ( glucosamine polymer) .
Algae possess cell walls made up of glycoproteins and polysaccharides.
Diatoms have cell walls made of biogenic silica.
Most land plants have cell walls made up of cellulose , hemicellulose and pectin ( polysaccharides) .
In growing plant cells, the cell wall is a cellulose - hemicellulose network embedded in a pectin matrix. This is called as the primary cell wall.
Secondary cell walls form ,when the cell is fully grown e.g. wood. These contain a wide range of additional compounds that modify their mechanical properties and permeability. Lignin ( phenolic polymer ) penetrates the space in the cell walls, driving out water and strengthening the wall.
The cell walls of cork cells in the bark of the trees are impregnated with suberin . This forms a permeability barrier.
The outer part of plant cell wall of plant epidermis is usually coated with cutin and wax ( plant cuticle ) .
Plant cell walls also contain enzymes ( hydrolases, esterases, peroxidases, transglycosylases ) that cut, trim and cross link cell wall polymers.
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