Question

describe the chemical composition of cell wall​

Answer 1

Cell Wall

★ Chemical composition

• The intercellular layer of the cell wall is basically composed of pectin.

If the pectin in plant tissue is broken down with pectinase , the cells will be dispersed, because the primary wall is composed of water, hemicellulose , pectin, cellulose, protein and lipids. The average value of the various components of the primary wall such as the coleoptile, stem, leaf, and hair is shown in the table. About 90% of the components that make up the cell wall are polysaccharides, and about 10% are proteins, enzymes, and fatty acids. The polysaccharides in the cell wall are mainly cellulose, hemicellulose and pectin , which are polymerized by glucose, arabinose , galacturonic acid and so on. There is also a lot of lignin in the secondary cell wall .

The animal's extracellular matrix is, in a sense, the cell wall, and its chemical composition is collagen , fibronectin , aminoglycan, and proteoglycans.

• The main component of the bacterial cell wall is peptidoglycan .The main components of fungal cell walls are chitin , cellulose, dextran , mannan, etc. These polysaccharides are polymers of monosaccharides.

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★ Formation

The formation of the cell wall is the result of a combination of various organelles. The formation of new cell walls begins in the late or early stages of cell division. During cell division, between the two sets of chromosomes, that is, on the surface of the equatorial plate of the mother cell (not actually present), there are many secretory vesicles (secretoryvesicles) of different sizes converging together in one piece. These small sacs The bubble is formed by the Golgi body and the endoplasmic reticulum, which is rich in various carbohydrates that constitute the cell wall. They are gradually arranged into pieces by the movement of the microtubules that are perpendicular to the equatorial plate of the cell Membrane body (phragmoplast). The vesicle membranes in the membrane- forming body are fused and connected to each other to form the plasma membrane of the cell, and the contents therein are integrated to form a cell plate, which is a prototype middle layer structure. After the cell plate is composed, the Golgi vesicles transport the wall-forming material out of the plasma membrane to fill the newly formed wall. When the cell plate is gradually filled and mixed with pectin and a small amount of cellulose molecules, it forms the middle layer, and the deposition of cellulose and hemicellulose and other substances on both sides of the middle layer forms a soft primary wall. At this time, two daughter cells are formed. Since then, most of the cells have layered and directional deposition of cellulose molecules inside the primary wall. They are cross-reinforced with longitudes and latitudes, which is an important basis for enhancing the supporting capacity of plants. The directional layered deposition of cellulose molecules is related to the activity of microtubules. Colchicine can prevent the formation of microtubules and inhibit the directional arrangement of cellulose molecules. Another important role of microtubules is to keep certain channels on the newly formed cell plate, that is, participate in the formation of intercellular ligaments, so that the protoplasts can maintain contact between the two daughter cells.

It can be seen that the formation of the cell wall is gradually completed in the process of living cell division, growth and differentiation. During cell division and the formation of new cell walls, in addition to the participation of Golgi apparatus , endoplasmic reticulum and microtubules , there are also the effects of auxin and various enzymes , and all activities rely on mitochondria to provide energy, which is reflected in The characteristics of the various parts of the cell cooperate with each other to complete life activities.

Answer 2

The Cell Wall of a plant is an extended extracellular matrix that envelops each cell in a plant

The Chemical Composition Of The Cell Wall Is:-

• All the cell walls in plant cells have their lineage in dividing cells, as the cell plate are formed during cytokinesis for creating a new partition wall between the daughter cells where the new cells are mostly produced in special regions known as meristems, and they are mainly small in comparison with their final size.

• To accommodate subsequent cell growth, their walls, called primary cell walls, are thin and extensible, although tough and are Built from Cellulose Microfibrils Interwoven which provide tensile strength with a Network of cellulose a network that is composed of pectin which is a highly hydrated network of polysaccharides rich in galacturonic acid.

• The secondary cell wall is produced by setting new layers inside the old ones and these may either have a composition which is similar to that of the primary wall or be markedly distinct. The extensively established additional polymer in secondary walls is lignin.

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