Plasma Membrane Definition

Plasma membrane refers to the membrane that surrounds the organelles of the cell, by creating a barrier between cell organelles and the external environment.

The plasma membrane is a thin membrane that surrounds every living cell, separating it from the external environment around it. The plasma membrane consists of water-soluble substances like nucleic acids, proteins, and carbohydrates. Typically, the plasma membrane defines the boundary of a cell. Apart from protecting the constituents of the cell, substances are exchanged through the surface of the plasma membrane.

The plasma membrane is composed of lipids and proteins that contribute to the functioning of the membrane. Even though the plasma membrane is the only barrier between internal components of the cell and the extracellular environment in some species. Some organisms have an extra-barrier, apart from the plasma membrane called the cell wall. Functions of plasma membrane include protection, selective permeability, cell signalling, endocytosis and exocytosis.

Main Article: Cell Membrane And Plasma Membrane – Major Differences

Frequently Asked Questions on Plasma Membrane Definition


Define plasma membrane.

The plasma membrane is defined as the boundary between the cell and its environment.


Is the plasma membrane permeable?

The plasma membrane is selectively permeable as it allows hydrophobic molecules and small polar molecules to diffuse through the lipid layer but does not allow ions and large polar molecules cannot diffuse through the membrane.

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