plasmolysis

Plasmolysis is a cellular process in which the plasma membrane pulls away from the cell wall as a consequence of water loss from the cytoplasm, typically when plant cells are placed in a hypertonic solution. This separation creates spaces between the membrane and the cell wall and is most easily observed in plant tissues because their cells contain a large central vacuole that regulates turgor pressure.

Mechanistically, exposure to a hypertonic environment causes water to exit the cytoplasm and vacuole via osmosis. As the internal pressure (turgor) falls, the plasma membrane constricts and detaches from the cell wall at certain points, while the cell wall remains rigid. The process is reversible: when plasmolyzed cells are returned to isotonic or hypotonic conditions, water re-enters the cytoplasm and the plasma membrane reattaches to the wall, a process known as deplasmolysis.

Plasmolysis occurs most readily in plant cells, some algae, and other organisms with cell walls. Animal cells do not typically undergo plasmolysis in the same way due to differences in cell structure and turgor dynamics, though they can experience similar membrane distortions under extreme osmotic stress.

Significance and uses include studying the relationship between the plasma membrane and the cell wall, assessing turgor pressure, and preparing protoplasts for experimental manipulation. It also provides a simple visual method for examining cellular responses to osmotic changes and can aid in understanding plasmodesmata function in plant tissues.