Which characteristic is common to both prokaryotic and eukaryotic cells?

Both prokaryotic and eukaryotic cells share a fundamental characteristic, which is the presence of a cell membrane. The cell membrane is a critical structure that surrounds the cell, providing a barrier that separates the internal environment of the cell from the external surroundings. It regulates the movement of substances in and out of the cell, thus maintaining homeostasis, allowing for nutrient intake, and facilitating waste elimination.

In prokaryotic cells, the cell membrane is crucial for processes such as cellular respiration and photosynthesis, depending on the type of prokaryote. Eukaryotic cells also have a cell membrane, but they may have additional structures like organelles and a more complex internal organization. The presence of a cell membrane is a universal feature of all cellular life, underpinning many basic functions essential for survival and function.