A cell can be considered as an ultramicroscopic living structure endowed with all the functions inherent in an organism. Cellular elements called organelles perform the function of respiration, reproduction, excretion, digestion. Lysosomes are one of the types of such organelles. They belong to single-membrane structures and perform specific functions associated with the digestion of substances and whole cellular elements located in the cytoplasm. In this work, we will study the structure of lysosomes and find out their role in the life support of the cell.
How organelles are formed
Representing single-membrane vacuoles filled with digestive enzymes, lysosomes form in the cisterns of the Golgi complex and are called primary. Through the channels of the apparatus, they enter the cytoplasm of the cell. As soon as lysosomes begin to absorb damaged cytostructures or break down organic substances, they are called secondary.
These organelles are filled with solutions of enzymes capable of breaking down molecules of carbohydrates, glycolipids and proteins. It is in the secondary lysosomes that biologically active substances such as proteases, sulfurylases and lipases are contained. The internal content of the organoid has a pH less than 7, since the above enzymes are active in an acidic environment. Organelles are capable of endocytosis or pinocytosis. The formation of lysosomes depends to a large extent on special proteins in the cell, formed on the channels of the granular endoplasmic reticulum.
The chemical composition of the matrix and the structure of the lysosome
Continuing to study the features of lysosomes, let's consider what substances form their internal environment. The complex of enzymes contains the most important of them: phosphorylase (breaks down amino acids), glucosidase (acts on glucose, cellulose, starch) and lipase (ensures the destruction of fat molecules, steroids).
The organelle's own membrane is resistant to the above enzymes. In some cases, it becomes vulnerable to their action, which leads to autolysis - the self-dissolution of the membrane, as a result of which the aggressive substances of the matrix are poured into the cytoplasm of the cell. This causes it to self-digest.
Organoid functions
It is well known how important reactions are in metabolic processes that promote the utilization of waste substances or parts of cellular structures, such as old mitochondria, ribosomes. The high enzymatic activity of organelles is manifested in those cells that are called phagocytic. This isfirst of all, the structures of the immune system: basophils, macrophages, neutrophils, B-lymphocytes. Primary lysosomes in these cells are quite large (up to 0.5 microns). They contain enzymes such as ribonuclease, protease, deoxyribonuclease. This composition is explained as follows: cells capable of phagocytosis primarily break down particles of viruses and bacteria containing proteins and ribonucleic acids.
An interesting mechanism that provides the proteolytic activity of the organelle. Foreign particles or molecules are first captured by the vacuole. The primary lysosome merges with it, which secretes hydrolytic enzymes. Now such an organelle, called a secondary lysosome, begins to actively digest the substances that have entered the matrix. The cleavage products further diffuse into the hyaloplasm of the cell, and undigested residues are stored inside the organelle, which is now called the residual body. The above structure of lysosomes of various types explains the main functions of these cell structures.
The role of organelles in the metabolic reactions of the human body
If insufficient enzymes are produced in lysosomes, their deficiency occurs, leading to severe hereditary diseases, such as metachromatic leukodystrophy. The structure of lysosomes in this pathology is abnormal. In their matrix, sulfatases, enzymes that break down cerebrosides, are absent or are in an inactive state. Being metabolic products in the cells of the nervous tissue, they are subject to utilization, but the absence of the corresponding enzymesleads to the accumulation of these compounds in neuroglia and hyaloplasm of neurocytes. This causes intoxication in the nervous tissue that forms the brain and spinal cord. As a result, the development of physical pathologies and mental retardation.
Thus, single-membrane organelles responsible for the breakdown of substances play a very important role in cellular metabolism. In this work, we studied the structure of lysosomes, found out their functions and significance in the life of the cell and the entire human body as a whole.
