Answer:
The plasma membrane
Explanation:
All cells have a structure called a plasma membrane or plasmalema, which is the outer life limit of the cell and acts as a barrier to both the release of cellular content into the medium and the flow of any particle into the cell. This feature thus shows an important structure selectability, which can range from 7 to 10 nm in thickness.
One of the main functions of the plasma membrane is to control what goes in and out of the cell, a property known as selective permeability. Because it is formed by a lipid bilayer, it is impervious to most water-soluble molecules. Because of this, the vast majority of ions and molecules require protein mediation to cross it. In addition to selective permeability, the plasma membrane has proteins that ensure the interaction between cells and the reception of signals from the environment.
