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Shrinking of the cytoplasm away from the cell wall due to exosmosis by immersion of a plant cell in a solution of higher osmotic activity.



the loosening of the protoplast from the cell cover when a cell is immersed in a hypertonic solution. Plasmolysis is characteristic mainly of plant cells, which have a sturdy cellulose cover. Animal cells contract when transferred to a hypertonic solution. Plasmolysis may be convex, concave, convulsive, or mitriform. These variations are determined by the viscosity of the protoplasm, the difference between the osmotic pressure of the cell and that of the external solution, and the speed and degree of water loss by the protoplasm. Sometimes plasmolyzed cells remain alive; when such cells are immersed in water or a hypotonic solution, deplasmolysis occurs.

There are two methods for comparative evaluation of plasmolysis: borderline plasmolysis and the plasmometric method. The first method, developed by H. de Vries in 1884, consists of immersing tissues in solutions with various concentrations of KNO3, sucrose, or other osmotically active substances and establishing the concentration at which 50 percent of the cells are plasmolyzed. With the plasmometric method, the relative volumes of the cell and the protoplast are measured after plasmolysis, and the osmotic pressure of the cell is calculated according to appropriate formulas from the concentration of the solution.


References in periodicals archive ?
Studies by Greenhill (1964) indicated that plant cell breakdown and the release of plant juices by plasmolysis is a prerequisite for the development of the LAB during the early stage of ensiling.
Arsenic toxicity in plants was described as consisting of root plasmolysis [32] and leaf wilting followed by root discoloration and necrosis of leaf tips and margins [57].
toxicity, ethylene production, plasmolysis, nutrient imbalance and interference with photosynthesis (Sairam and Tyagi 2004).
Larger amounts of mineral salts (KCl, NaCl) evoke plasmolysis inside the cells of microorganisms as a result of which microorganisms are destroyed.
The midrib shows cellular plasmolysis and consequent formation of large intercellular spaces, as well as hypertrophy of the parenchyma cells and intense coloration caused by fuchsine in the affected areas (Figures 2b and 2c).
This process is called plasmolysis and is, of course, disastrous for the cell.