Cells of plants and animals contain a number of structures that ensure their vital functions. One of them is vacuoles. Between themselves, they have a number of significant differences. From our article you will learn what vacuoles are and why living organisms need them.
Permanent cell structures
Vacuoles are single-membrane organelles of plant and animal cells. Some of them are permanent structures, others arise as they are functionally necessary. Depending on the structural features, these organelles are able to store nutrients, break them down and perform a regulatory function.
Types of structures
There are three kinds of vacuoles. In the cells of the simplest animals are contractile and digestive. They regulate 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 allinternal content. And it's easy to explain. After all, a growing organism needs a lot of reserve substances for development. What are plant cell vacuoles? These are large single-membrane reservoirs with cell sap. The latter is water with dissolved carbohydrates and residues of inorganic substances. The composition of cell sap also includes a variety of metabolic products. It can be alkaloids, tannins. It also contains pigments that give color to various 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 a regulatory function, is completely different. Most of these structures are found in the cells of freshwater and marine protozoa. What are vacuoles that regulate cell turgor? They are pulsating bubbles around which there is a network of tubules. These are transport routes for liquid. Through the tubules, excess fluid first enters the vacuole from the cytoplasm, and is already removed from it.
Where does excess fluid come from in the cell and why should it be removed? It's all about the laws of physics. According to them, movement occurs from an area with a higher concentration to a lower one. Since there are more s alts in the environment, water begins to flow into the cell. Its surface apparatus may simply not withstand such pressure. And thanks to contractile vacuoles, the same level of osmotic pressure and balance with the environment are maintained.
Digestive vacuoles
Digestive vacuoles break down complex substances into simple ones that organisms can absorb. These structures are non-permanent formations. They arise in that part of the cytoplasm where food particles are located. It can be both solid particles and liquids. A single-membrane vesicle containing hydrolytic enzymes is formed around them. Depending on the nature of the content, the environment in it changes 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, food enters the cytoplasm and is absorbed by the body. Its undigested residues are excreted through cell membranes or specialized formations.
So, in our article we examined what vacuoles are, got acquainted with their diversity. Depending on the structural features, they are able to store substances, break them down or remove them from the cell and its structures.
