What is the main role of cell walls in bacteria?

The main role of cell walls in bacteria is to provide structural support against osmotic pressure. The cell wall is a rigid structure that surrounds the bacterial cell membrane, and it plays a crucial role in maintaining the shape and integrity of the bacteria.

Bacteria often inhabit environments where the osmotic pressure can vary significantly, such as freshwater or saline conditions. When bacteria are exposed to hypotonic environments where the external concentration of solutes is lower than that inside the cell, water can rush into the cell. The cell wall counters this influx of water, preventing the cell from bursting due to excessive internal pressure. This protective function is essential for the survival of bacteria in diverse environments.

In contrast, the cell wall does not prevent the entry of all substances; rather, it selectively allows certain molecules to pass through, which is a function of the cell membrane more than the wall itself. Additionally, while bacteria may use various mechanisms for transport, such as active transport, this is not a primary role of the cell wall. Similarly, regulation of temperature is generally a cellular function rather than one governed by the cell wall.