What are vacuoles: types and features of structures

Cells of plants and animals contain a number of structures that fulfill their vital functions. One of them are vacuoles. Between them, they have a number of significant differences. From our article you will find out what vacuoles are and why they are necessary for living organisms.

Constant cell structures

Vacuoles are called single-membrane organelles of plant and animal cells. Some of them are permanent structures, others arise as far as their functional necessity. Depending on the characteristics of the structure, these organelles are able to store nutrients, split them and perform a regulatory function.

Types of structures

There are three types of vacuoles. In plant cells there are contractile and digestive. They regulate the osmotic pressure, remove undigested residues and perform a secretory function. But in plants, these are large reservoirs containing water, in which all the substances necessary for the cell are dissolved.

Vacuoles in a plant cell

In young plant cells, these structures can occupy almost all the internal contents. And it's easy to explain. After all, a growing body needs a lot of reserve substances for development. What are vacuoles of plant cells? These are large single-membrane reservoirs with cell sap. The latter is water with dissolved carbohydrates and residues of inorganic substances. The composition of the cell juice also includes a variety of metabolic products. It can be alkaloids, tannins. There are also pigments that give color to different parts of plants. Thus, the vacuole in the plant cell plays the role of a kind of "pantry".

Contractile vacuoles

The structure of the vacuole, which performs the regulatory function, is quite different. Most of these structures occur in cells of freshwater and marine protozoa. What are the vacuoles that regulate the turgor cells? They are pulsating bubbles, around which there is a network of tubules. These are transport routes for liquid. On the tubules, the excess fluid first comes from the cytoplasm into the vacuole, and from it is already outward.

Where does the superfluous liquid in the cell come from and why should it be removed? It's all about the laws of physics. According to them, the movement comes from an area with a greater concentration to a smaller one. As there are more salts in the environment, water begins to flow into the cell. Its surface apparatus may simply not withstand such pressure. And thanks to the contractile vacuoles, the same level of osmotic pressure and equilibrium with the environment are maintained.

Digestive vacuoles

Digestive vacuoles split complex substances to simple ones that are able to assimilate organisms. These structures are unstable formations. They arise in the part of the cytoplasm where food particles are located. It can be both solid particles and liquids. A single-membrane vesicle containing hydrolytic enzymes forms around them. Depending on the nature of the content, the medium in it varies from acidic to alkaline. These biologically active substances accelerate chemical reactions, but are not part of its products. Further through the wall of the vacuole, the food enters the cytoplasm and is absorbed by the body. Its undigested residues are secreted through the cell membrane or specialized formations.

So, in this article we have examined what the vacuoles are, they have become acquainted with their diversity. Depending on the characteristics of the structure, they are capable of storing substances, splitting them, or withdrawing them from the cell and its structures.