Functions of the cell wall: supporting, transport, protective

Surface apparatus is an integral part of any cell and many of its components. It performs vital functions. How the cell membrane works , the structure and functions of this structure - everything will be discussed in our article.

Cell membrane system

Everyone knows that the cell is the smallest structural and functional unit of the body, and its main parts are the surface apparatus, cytoplasm and organelles. However, its structure can be considered in a different way. Any cell is a system of biological membranes. In Latin, this term means "film" or "peel". So, on top the cells are covered with a plasma membrane. But the inner environment of the cell is divided into separate segments with the help of similar internal structures. Such a structure provides spatial placement of various elements and chemical processes.

Structure and function of cell membranes

The existing model of the structure of biological membranes is called liquid-mosaic. It is based on a double layer of lipids, the hydrophilic parts of which are facing outward. These are phosphate groups of these substances. But the hydrophobic parts of lipids, which are compounds of fatty acids, face the bilayer. The next component of cell membranes are proteins. Some of them are superficial and are located outside, others permeate a double layer of lipids at different depths. This structure allows the cell to carry out complex defense, diffusion, phage and pinocytosis processes.

Overmembrane cell complexes

The complexes carrying out additional functions are located above the plasma membrane . In plant cells, fungi and bacteria, they are represented by a cell wall. But animals have a similar structure is glycocalyx. It provides a direct connection of the cell with the environment, regulating the selective intake of substances. The functions of the cell wall are due to its structural features, which are somewhat different from the similar structure of animal cells.

Composition of the cell wall

The chemical structure of the cell wall in different groups of organisms is somewhat different. In plants it is the densest. This property is ensured by the presence of insoluble cellulose fibers collected in bundles. It is this complex carbohydrate that gives the cell walls of plants rigidity and strength. You can say that it forms a kind of skeleton. The composition and function of the cell wall in different types of tissues can vary considerably. For example, over time, cells of one of the types of cover tissue, which is called cork, are impregnated with the fatty substance suberin. The result is the withering away of the internal contents and the provision of a supporting function. A similar process is observed in cells of the conducting tissue of plants, viz. In vessels. They become hollow structures, as a result of which it becomes possible to carry out the substances. The process of lignification is due to the fact that the gaps between the fibers of cellulose fill another complex carbohydrate - lignin. It significantly increases the strength of the surface apparatus.

In fungi, the basis of the cell wall is also composed of polysaccharides. However, predominant is not cellulose, but chitin and glycogen. This is a feature of the structure that makes them related to animals. But the function of the bacterial cell wall provides a complex connection of carbohydrates and proteins. It is called peptidoglycan or murine. This substance is characteristic only of cells of prokaryotic organisms and performs mechanical functions.

Functions of the cell wall

Despite significant differences in the chemical composition, the cell walls of different groups of organisms have a similar specialization. Their main functions are to provide support, protection and metabolism. The cell wall maintains a constant shape. It protects all internal contents from the mechanical effects of the environment. Functions of the cell wall are also in the implementation of a continuous process of water entering the cell with nutrients dissolved in it and in the opposite direction.

Permeability of the cell wall

The process of metabolism, which carries out the cell wall, is possible due to its permeability. This property is manifested in the implementation of two inverse processes. The first is called plasmolysis. It consists in the detachment of the cytoplasm layer located directly near the cell wall. For this, certain conditions are necessary. Plasmolysis occurs, for example, by placing a cell with a higher salt concentration than in its own cytoplasm. The reverse process is called deplasmolysis.

Thanks to the pores that are in the cell walls, there is also a metabolism between the cells. This is done directly with the help of plasmodesm. These formations are a way of transporting substances. They pass through the plasma membrane and are hollow tubes that connect the EPS of neighboring cells. It is in these organelles that the synthesis and accumulation of all substances necessary for the development of organisms occurs.

So, the cell membrane, the structure and functions of which we have considered in our article, is typical for all organisms. In plant and bacterial organisms, as well as fungi, a cell wall is located above it. It is formed by polysaccharides, which give it strength. The main functions of the cell wall are protection, support and transport of substances.