Yes, both animal and plant cells have a cell membrane.

Here's why the cell membrane is so important:

* Selectively Permeable: It controls what enters and exits the cell, allowing some substances to pass through while blocking others. This is crucial for maintaining the cell's internal environment and carrying out essential processes.

* Protection: It acts as a barrier, protecting the cell's internal components from the external environment.

* Communication: It contains receptors that allow the cell to communicate with its surroundings and other cells.

Note: Plant cells also have a cell wall outside their cell membrane. The cell wall provides additional structural support and protection for the plant cell.