A cell can be considered as an ultramicroscopic living structure, endowed with all the functions inherent in the body. Cell elements called organelles perform the function of respiration, reproduction, excretion, and 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 paper, we study the structure of lysosomes and find out their role in the life support of the cell.
How are organelles formed?
Representing single-membrane vacuoles filled with digestive enzymes, lysosomes are formed in the tanks 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 enzyme solutions capable of breaking down carbohydrate, glycolipid and protein molecules. It is in the secondary lysosomes that such biologically active substances as proteases, sulfurylases and lipases are contained. The internal content of the organoid has a pH of 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 peculiarities of lysosomes, we consider what particular substances form their internal environment. The enzyme complex contains the most important of them: phosphorylase (breaks down amino acids), glucosidase (acts on glucose, cellulose, starch) and lipase (provides the destruction of fat molecules, steroids).
Own organelle membrane is resistant to the above enzymes. In some cases, it becomes vulnerable to their action, which leads to autolysis - self-dissolution of the membrane, as a result of which aggressive substances of the matrix are poured into the cytoplasm of the cell. This leads to its self-digestion.
Organoid Functions
It is well known how important reactions are in metabolic processes that contribute to the disposal 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 is primarily the structure 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 break down primarily particles of viruses and bacteria containing proteins and ribonucleic acids.
An interesting mechanism is the proteolytic activity of the organelle. Foreign particles or molecules are first captured by a vacuole. The primary lysosome merges with it, which secretes hydrolytic enzymes. Now, such an organelle, called the secondary lysosome, begins to actively digest the substances received in the matrix. The cleavage products further diffuse into the cell hyaloplasm, and undigested residues are stored inside the organelle, which is now called the residual body. The above structure of lysosomes of various species and explains the main functions of these cellular structures.
The role of organelles in the metabolic reactions of the human body
If the enzymes in the lysosomes are not produced enough, there is a deficiency leading to severe hereditary diseases, for example, metachromatic leukodystrophy. The structure of lysosomes with this pathology is abnormal. In their matrix, sulfatases, enzymes that break down cerebrosides, are absent or inactive. Being metabolic products in the cells of the nervous tissue, they must be disposed of, but the absence of the corresponding enzymes leads to the accumulation of these compounds in the neuroglia and hyaloplasm of the neurocytes. This causes intoxication in the nerve tissue that forms the brain and spinal cord. As a result, the development of physical pathologies and mental retardation.
Thus, the 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.