What is the structure responsible for transport in a cell?

The structure responsible for transport in a cell is primarily the cell membrane, also known as the plasma membrane. It is a phospholipid bilayer embedded with proteins that facilitate the movement of substances in and out of the cell. Additionally, various organelles, such as the endoplasmic reticulum and Golgi apparatus, play key roles in intracellular transport and processing of proteins and lipids. Together, these structures ensure the proper distribution of materials essential for cellular function.