What is the main function of the cell membrane?

The primary function of the cell membrane is to regulate the entry and exit of substances. It acts as a selective barrier, controlling what can move in and out of the cell. This selective permeability is vital for maintaining homeostasis, as it allows essential nutrients to enter, waste products to leave, and helps protect the internal environment of the cell from potentially harmful substances.

The cell membrane is composed of a phospholipid bilayer with embedded proteins, which facilitate this regulation. Some proteins act as channels or carriers for specific molecules, while others serve as receptors to detect signals from the environment. This dynamic nature of the cell membrane is crucial for various cellular processes, including communication, nutrient uptake, and waste removal.

In contrast, energy production mainly occurs in organelles like mitochondria, while protein synthesis takes place in ribosomes. Providing structural support is more directly associated with the cell wall in plant cells and the cytoskeleton, rather than the cell membrane itself.