What is the primary function of the plasma membrane in a cell?

The primary function of the plasma membrane is to protect the cell from its surroundings. It acts as a barrier that regulates the movement of substances in and out of the cell, ensuring that essential nutrients can enter while waste products and harmful substances are kept out. This selective permeability is crucial because it maintains the internal environment of the cell, allowing it to function optimally. The plasma membrane is composed of a phospholipid bilayer with embedded proteins, which aids in transport and communication with other cells. Additionally, it plays a significant role in cell signaling and maintaining the overall integrity and dynamics of the cell, contributing to both the protection and proper functioning of the cell.