Cell membrane and its biological role

Today, for most people, it's no secret thatmembranes are the key link in the regulation of biochemical processes in the cell. Thanks 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,which 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 arelipids (60-70%) - phosphatidylcholine, phosphatidylethanolamine, sphingomyelin and cholesterol. Cholesterol imparts rigidity to biological membranes, 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 structure of 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 barrierfunction, which 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.

Transport function of biomembranes providesthe 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 bilipid layer, they penetrate with specific carrier proteins, and also through endocytosis. Passive types of transproportion of substances inside the cell include diffusion. Active transport of substances is carried out with the participation of a potassium-sodium pump.

The matrix function of the membranes is due tocertain 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.

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