Which part of the cell is selectively permeable?

The cell membrane is selectively permeable, meaning it allows certain substances to pass through while blocking others. This selective permeability is crucial for maintaining homeostasis within the cell, as it regulates the intake of nutrients and the expulsion of waste products. The structure of the cell membrane, characterized by a phospholipid bilayer with embedded proteins, facilitates this selective transport. Proteins act as channels or carriers to help specific molecules cross the membrane, ensuring that the cell can control its internal environment effectively.

In contrast, while the nucleus, endoplasmic reticulum, and Golgi apparatus play vital roles in cell function, they do not perform the selective permeability function attributed to the cell membrane. The nucleus encloses genetic material, and the endoplasmic reticulum and Golgi apparatus are involved in protein and lipid synthesis and modification; however, they do not directly manage the selective transport of substances into and out of the cell.