Cell membrane and its biological role

Today, for most people, it's not a secret that membranes are the key link in the regulation of biochemical processes in the cell. Due to biological membranes, internal homeostasis is maintained inside the cell. The cell membrane highly selectively regulates the rate of penetration of various biological compounds into the cell, as well as the release of enzymes and vectors from it. In addition, this structure has a complex biological complex that provides perception, transformation, as well as the transfer of information from the external environment into the cell.

The cell membrane is a structure that limits cells and intracellular organelles (lysosomes, mitochondria, Golgi complex , etc.). Each cell is an integral system of membranes constructed from tubules, pouches and cisterns. Biological membrane - thin plates (60-70%) of lipoprotein and glycoprotein nature. It should be noted that bacterial and plant cells, in contrast to animals, are unable to change their shape, since they are surrounded by a dense cell wall. The cell membrane of plant organisms consists of polysaccharides, bacteria from monosaccharides, amino sugars, lipids and amino acids.

The structure of the cell membrane.

The main components of cell membranes are lipids (60-70%) - phosphatidylcholine, phosphatidylethanolamine, sphingomyelin and cholesterol. Cholesterol makes the biological membranes stiff, so membranes with a small concentration of cholesterol are more elastic. Membrane proteins are represented by lipoprotein and glycoprotein complexes (30-35%). The cell membrane in a small amount also contains carbohydrates in the composition of glycoproteins, glycolipids, and glycosaminoglycans (5-10%). The composition of the cell membranes includes minor compounds (nucleic acids, antioxidants, inorganic ions, coenzymes, etc.). Plasma membranes are closely related and form a single whole with intracellular membranes of the endoplasmic reticulum (reticulum). The composition of the reticulum includes granular and agranular membranes of the endoplasmic reticulum, which divide the inner space of the cell into many compartments. This is of great importance in the process of regulation of intracellular transport of substances and the flow of metabolic processes.

Functions of the cell membrane.

Cell membranes provide a barrier function that manifests itself in the form of selective, controlled metabolism with the environment. Due to the selective permeability, only substances of a certain size can enter the interior of the cell.

The transport function of biomembranes ensures the transfer of nutrients into the cell and the removal of the final metabolites from it. The cell membrane is involved in maintaining the optimal pH. Those compounds that are unable to cross the bilipidic layer, they penetrate with the help of specific carrier proteins, and also through endocytosis. To passive types of transproportion of substances inside the cell can be attributed diffusion. Active transport of substances is carried out with the participation of a potassium-sodium pump.

The matrix function of membranes is due to a certain interposition and orientation of membrane proteins. Cell walls play a significant role in providing a mechanical function, and in intercellular substances in animals. The receptor function is due to the presence of special proteins that are localized on the cell membrane.

The enzymatic function of biological membranes is associated with membrane proteins, as well as enzymes. For example, plasma membranes of epithelial cells (epithelial cells of the intestine) contain digestive enzymes.