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Wood is a structural tissue/material found as xylem in the stems and roots of trees and other woody plants.It is an organic material – a natural composite of cellulosic fibers that are strong in tension and embedded in a matrix of lignin that resists compression.
An example of this is that secondary wall in wood contains polysaccharides called xylan, whereas the primary wall contains the polysaccharide xyloglucan. The cells fraction in secondary walls is also higher. [7] Pectins may also be absent from the secondary wall, and unlike primary walls, no structural proteins or enzymes have been identified. [4]
Its most commonly noted function is the support through strengthening of wood (mainly composed of xylem cells and lignified sclerenchyma fibres) in vascular plants. [17] [18] [19] Finally, lignin also confers disease resistance by accumulating at the site of pathogen infiltration, making the plant cell less accessible to cell wall degradation. [20]
In plants, a secondary cell wall is a thicker additional layer of cellulose which increases wall rigidity. Additional layers may be formed by lignin in xylem cell walls, or suberin in cork cell walls. These compounds are rigid and waterproof, making the secondary wall stiff. Both wood and bark cells of trees have secondary walls.
Cellulosic sugars are derived from non-food biomass (e.g. wood, agricultural residues, municipal solid waste). [1] The biomass is primarily composed of carbohydrate polymers cellulose, hemicellulose, and an aromatic polymer (lignin). The hemicellulose is a polymer of mainly five-carbon sugars C 5 H 10 O 5 .
A section of rosemary stem, an example of a woody plant, showing a typical wood structure. A woody plant is a plant that produces wood as its structural tissue and thus has a hard stem. [ 1 ] In cold climates, woody plants further survive winter or dry season above ground, as opposed to herbaceous plants that die back to the ground until spring .
Protein domains. The two shown protein structures share a common domain (maroon), the PH domain, which is involved in phosphatidylinositol (3,4,5)-trisphosphate binding. Proteins are frequently described as consisting of several structural units. These units include domains, motifs, and folds.
The structural components of plants are formed primarily from cellulose. Wood is largely cellulose and lignin, while paper and cotton are nearly pure cellulose. Cellulose is a polymer made with repeated glucose units bonded together by beta-linkages.