Plasmolysis is an osmotic process in the cells of plants, fungi and bacteria, associated with their dehydration and retreat of the liquid cytoplasm from the inner surface of the cell membrane with the formation of cavities. This is possible due to the presence of a cell wall, which provides a rigid outer framework. Deplasmolysis is the reverse process, that is, the restoration of the original shape of the cell with a decrease in osmotic pressure in the extracellular fluid.
Origin of plasmolysis and deplasmolysis
Plasmolysis occurs in the cells of fungi, plants and bacteria, which have a strong cell wall. When they are in a hypertonic solution, the concentration of electrolytes in which is greater than in the cytoplasm, water is released into the intercellular space. Depending on the degree of dehydration, cell plasmolysis is divided into angular with minimal cytoplasm retreat, concave, convulsive, cap and convex.
Prone to partial deplasmolysisall of these variants of plasmolysis, but full cell viability can be restored only in the case of convulsive, angular, concave plasmolysis, since it develops either on a small scale or does not lead to damage to intracellular structures. Convex plasmolysis is a completely irreversible process. It partially resembles the convulsive variant in shape, but the latter is often reversible.
Osmotic phenomena in the cell
Such phenomena as plasmolysis and deplasmolysis are mutually opposite. Plasmolysis is the contraction of a cell when it is in a hypertonic solution. Deplasmolysis is the restoration of the original shape and size of a cell that has previously undergone plasmolysis. Plasmolysis is an osmotic phenomenon that occurs in plant and bacterial cells, as well as in fungal cells.
An important condition for its development is the presence of a cell wall, a rigid frame that provides a constant shape and size. In them, this phenomenon can be described as a process of wrinkling of the internal environment of the cell due to the release of fluid into the intercellular space and the formation of cavities between the receded cytoplasm and the cell membrane. That is, the mobile cytoplasm, losing fluid, shrinks and releases the cavities between the cell membrane and its internal environment.
Household example of plasmolysis and deplasmolysis
Plasmolysis of plant cells, fungi and bacteria is a reversible process. At the same time, bacteria whose cells have a cell wall can be in this state for a very long time. But once in a favorable environment, they are able to recover andcontinue your life. A household example of plasmolysis and deplasmolysis is the preparation of jam. In a solution with a high concentration of sugar, plasmolysis occurs. This ensures the safety of the product for a long time, since bacteria cannot carry out their vital activity.
When using jam, when the osmotic pressure in the solution decreases, the bacterial cell becomes active again. This means that such a phenomenon as deplasmolysis is taking place - the restoration of the gel-sol properties of its cytoplasm and normal performance. If there is a sufficient amount of pathogenic microflora in the solution, then it is quite capable of causing an infectious disease.
Osmotic phenomena in animal cells
Extreme variant of animal cell deplasmolysis is erythrocyte hemolysis. It is destroyed in hypotonic solutions due to its excessive swelling. Due to the lower concentration of electrolytes on the outside of the red blood cell, water rushes through the membrane inward to equalize the osmotic pressure. However, due to the limited internal space of the cell and its low capacity, membrane rupture and hemolysis occur. The plant cell is more durable due to the presence of a cell wall, and therefore its swelling often does not lead to lysis. At a certain moment, the hydrostatic pressure inside the cell equalizes with the osmotic pressure, which stops the further flow of water into the cytoplasm.
In hypertonic solutions in erythrocytes, the opposite phenomenon occurs - wateris removed from the cytoplasm, and the cell shrinks. However, in highly developed multicellular organisms, the limit of osmotic action is very low. Therefore, the cell dies more often, since it cannot remain viable for a long time in the presence of a very viscous cytoplasm. Moreover, in the human body, each cell must perform certain functions, and not just exist. A cell that "does not work" will be eliminated by macrophages.
