Cells surrounded by a cell wall, such as bacterial cells, are able to resist changes in the osmotic environment of their surroundings due to the presence of the cell wall. The cell wall is a rigid structure made up of peptidoglycan, which is permeable to small molecules like water and ions but restricts the passage of larger molecules.
When a bacterial cell is placed in a hypotonic solution, such as distilled water, water will move into the cell due to the difference in solute concentration between the inside and outside of the cell. This can cause the cell to swell and potentially burst. However, the presence of the cell wall provides mechanical support to the cell, preventing it from bursting.
Conversely, when a bacterial cell is placed in a hypertonic solution, such as a high concentration of salt, water will move out of the cell, causing it to shrink. However, the cell wall helps to maintain the shape of the cell and prevents it from collapsing.
In both cases, the cell wall enables the cell to maintain its shape and integrity despite changes in the osmotic environment. This allows cells surrounded by a cell wall to be grown in media with an osmotic strength much less than that of the cytosol, since the cell wall provides the necessary mechanical support to resist changes in osmotic pressure.
