What is the primary function of the cell membrane?

The primary function of the cell membrane is selective permeability, which refers to its ability to control what substances can enter and exit the cell. The cell membrane is composed of a lipid bilayer that contains embedded proteins. This structure allows the cell to maintain a stable internal environment, or homeostasis, by selectively allowing certain ions and molecules, such as nutrients and waste products, to pass through while blocking others.

This selective barrier is crucial for cellular functions as it enables cells to take in essential substances and remove harmful ones. The proteins within the membrane play various roles, including acting as channels or transporters to facilitate the movement of specific molecules across the membrane, further contributing to its selective permeability.

In contrast, energy production is primarily associated with organelles like mitochondria, genetic information storage is the function of the nucleus where DNA resides, and protein synthesis occurs mainly in the ribosomes in the cytoplasm or on the rough endoplasmic reticulum. Each of these functions is vital for cellular operation but does not pertain to the core role of the cell membrane.