What is the primary function of the cell membrane?

The primary function of the cell membrane is to regulate what enters and leaves the cell. This selective permeability is crucial for maintaining the internal environment of the cell, allowing it to control the concentrations of various substances, nutrients, and waste products. The cell membrane consists mainly of a phospholipid bilayer with embedded proteins that facilitate communication and transport across the membrane. This structure ensures that essential molecules like glucose and ions can enter the cell while waste products can be removed efficiently.

The ability of the cell membrane to participate in processes such as diffusion, osmosis, and active transport allows the cell to maintain homeostasis and respond to changes in its environment. In contrast, while structural support is important for cells, it is primarily provided by the cytoskeleton and the cell wall in plant cells. Storing genetic information is the function of the nucleus, and converting energy into usable forms is primarily carried out by mitochondria and chloroplasts in eukaryotic cells. Therefore, the regulation of substances moving in and out of the cell stands out as the key role of the cell membrane.