Define following Lignin subrin and cutin?
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Answer:
Lignin is a chemical compound derived from wood and is found in the secondary cell walls of plants. It is a polymer of aromatic subunits derived from phenylalanine. Lignin is found in the spaces in the cell wall between cellulose, hemicelluloses and pectin components. It is covalently linked to hemicelluloses. It is cross linked to different polysaccharides and thus provides mechanical strength to the cell wall and also to the whole plant. Lignin polymers are hydrophobic and hence impermeable to water whereas the polysaccharides are permeable to water.
It constitutes about 30% of dry weight in woody plants and is the most abundant organic compound after cellulose. The lignin content varies considerably even within plants of the same species.