Why is plasma membrane called selectively permeable membrane.

Why is plasma membrane called selectively permeable membrane.


Selectable permeable membrane are also called plasma membrane . It allows only the movement of certain molecules in and out of the cells. Not all molecules can diffuse. When the plasma membrane ruptures or breaks down, the molecules of certain substances move freely in and out of the cells.

Because the plasma membrane acts as a mechanical barrier, it does not transfer substances from its surroundings through osmosis or cell proliferation. As a result, the tissue dies due to the disappearance of the protoplasmic material. It allows hydrophobic molecules and small polar molecules to diffuse through the lipid layer, and does not allow the ions and large polar molecules cannot diffuse through the membrane.

Proteins in the plasma membrane.

There are two types of protein molecules in the plasma membrane:


    1. Integral membrane proteinsThis proteins are, as their name implies, are integrated into the membrane. They have at least one hydrophobic region that binds to the hydrophobic core of the phospholipid bilayer. Some stick only partially to the membrane, while others extend from one side of the membrane to the other and are exposed on both sides. Transmembrane proteins are proteins that spread throughout the membrane.

    2. Peripheral membrane proteins – These occur on the outer or inner surface of the lipid layer. Peripheral membrane proteins are found on the outside and inside of the skin. This proteins attached to integral proteins or phospholipids. Unlike integral membrane proteins, peripheral membrane proteins do not adhere to the hydrophobic core of the membrane and are more flexible.

Functions of the plasma membrane.

  • The plasma membrane creates a barrier between the cell organs from the external environment.
  • only allowed to pass certain molecules.
  • It is helpful the cell for communication and signaling.

This article about why plasma membranes are called selectable permeable membranes. We explained all its features. This is helpful for all visitors looking for it. Only we used simple sentences and illustrations for better understand.