What is the term for the semi-permeable nature of the cell membrane?

The term that describes the semi-permeable nature of the cell membrane is selective permeability. This concept refers to the ability of the cell membrane to allow certain substances to pass through while restricting others. This selective process is vital for maintaining the internal environment of the cell, ensuring that essential molecules such as nutrients can enter, while waste products and harmful substances are kept out.

Cell membranes are primarily composed of a phospholipid bilayer embedded with proteins, which facilitates this selective transport. This means that only molecules that fit specific criteria, such as size, charge, and solubility, can cross the membrane freely, while others require specific transport mechanisms or channels. Thus, selective permeability is crucial for cellular function, homeostasis, and communication between cells.