It's essential for their survival. The cell membrane:

* Controls what enters and exits the cell: This is crucial for maintaining the internal environment, taking in nutrients, and removing waste products.

* Provides structural support: The membrane helps maintain the shape and integrity of the cell.

* Acts as a barrier: It separates the cell's internal environment from the external environment.

While prokaryotes don't have the same complex membrane-bound organelles as eukaryotic cells, the cell membrane is a fundamental component of their structure and function.