Question

Cell wall consists of
A. Lignin , hemicellulose , pectin and lipid
B. Hemicellulose pectin protein and lipid
C. Cellulose Hemicellulose pectin and lignin
D. Cellulose hemicellulose tubulin and lignin

Answer 1

Hint: Cell wall, a specialised type of extracellular matrix that surrounds every cell in a plant. The cell wall is responsible for many of the characteristics which distinguish plant cells from animal cells.

Complete Answer:
Although the primary and secondary wall layers vary in their detailed chemical composition and structural organisation, their basic architecture is the same, consisting of high tensile strength cellulose fibres embedded in a water-saturated matrix of polysaccharides and structural glycoproteins.

Cellulose consists of several thousand glucose molecules connected to the end. Chemical connections between the individual glucose subunits give each cellulose molecule a flat ribbon-like structure that allows adjacent molecules to band together laterally into microfibrils with lengths varying from two to seven micrometres.The enzymes floating in the cell membrane synthesise cellulose fibrils and are arranged in a rosette configuration. Each rosette appears capable of "spinning" through the cell wall of a microfibril.

Polysaccharides from the matrix: Hemicelluloses and pectic polysaccharides, or pectins, are the two main groups of polysaccharides of the cell wall matrix. In the Golgi apparatus, both are synthesised, carried to the cell surface in tiny vesicles, and secreted into the cell wall.

Hemicelluloses consist of end-to-end glucose molecules arranged as in cellulose, with short side chains connected to one side of the ribbon of xylose and other uncharged sugars. The other side of the ribbon attached tightly to the cellulose fibril surface, thereby covering the microfibrils with hemicellulose and uncontrollably preventing them from adhering together.

In important respects, the heterogeneous, branched, and highly hydrated pectic polysaccharides differ from hemicelluloses. In particular, they are negatively charged because of the residues of galacturonic acid, which along with the molecules of rhamnose sugar, form the linear backbone of all pectic polysaccharides.

Proteins: Although plant cell walls contain only small quantities of protein, they serve a range of significant functions. Cell walls contain a variety of enzymes in addition to structural proteins. Those that cross-link extension, lignin, cutin, and suberin molecules into networks are the most prominent.

Plastics: A number of organic compounds cross-linked into tight three-dimensional networks include cell wall plastics such as lignin, cutin, and suberin, all of which reinforce cell walls and make them more resistant to fungal and bacterial attacks. The general name for a complex group of aromatic alcohol polymers is lignin. Deposited mainly in secondary cell walls, it accounts for up to 30 percent of the dry weight of a plant, supplying the rigidity of terrestrial vascular plants.

The correct Answer is option C, Cellulose Hemicellulose pectins and lignin.

Note: In the 4:3:3 ratio, the plant cell wall consists of cellulose, hemicellulose and lignin. In addition to describing the form of plant cells, a cell wall has a few other functions, including preserving a cell's structural integrity, serving as a line of defence against a variety of external factors, as well as hosting various channels, pores and receptors that regulate a cell's different functions.