What is the primary function of the cell membrane?

The primary function of the cell membrane is to protect the cell and regulate what enters and leaves. This semi-permeable barrier is crucial for maintaining the internal environment of the cell, allowing essential nutrients to enter while keeping harmful substances out. The cell membrane achieves this through a phospholipid bilayer embedded with proteins that facilitate transportation and communication.

In addition to its protective role, the membrane participates in signaling and transport processes that are vital for the cell's function and integrity. It helps maintain homeostasis by controlling the exchange of ions, molecules, and waste products. Thus, the cell membrane plays a critical role in both the physical protection of the cell and in the selective absorption and secretion processes essential for cellular health and function.