Plasma membrane and cell membrane are often mistaken for different concepts. However, both terminologies refer to the same concept:
Plasma membrane / Cell membrane refers to the biological membrane which separates the interior of the cell from the cell’s extracellular space.
The Rise of Different Terminologies:
Throughout history, various scientists and biologists have referred to this structure by many names. The term “plasma membrane” was originally derived from the German word “Plasmamembran”, a word coined by Carl Wilhelm von Nägeli – a Swiss botanist who used this term to describe the thin film that forms when the sap of an injured cell comes in contact with water.
Moreover, the term “protoplasm” was in use before the advent of electron microscopy and differential centrifugation – which means it was difficult to help identify cell organelles and other cellular structures unambiguously. Hence, one could say that the term “plasma membrane’ is deemed obsolete by today’s standards.
Other less common and (obsolete) terms that refer to the plasma membrane include:
- Plasmatic membrane
- Cytoplasmic membrane
Cell Membrane / Plasma Membrane Function
Following are the major functions of the plasma membrane/cell membrane:
- It regulates the entry and exit of substances in the cell.
- Protects a cell from bacteria, viruses and other invading pathogens.
- It also plays a major role in cell signalling.
- Provides a selective barrier that allows only certain molecules to enter and exit the cell.
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Frequently Asked Questions
Is plasma membrane and cell membrane the same thing?
Yes, the plasma membrane and cell membrane are the same. Both refer to the biological membrane which separates the interior of the cell from the cell’s extracellular space.
What is the function of the plasma membrane?
The plasma membrane protects the cell from its surroundings. It is a selectively permeable membrane that regulates the entry of certain ions and molecules.
Do eukaryotic cells possess a plasma membrane?
Both eukaryotic and prokaryotic cells possess plasma membranes.
Do animal cells possess a plasma membrane?
Animal cells do possess a plasma membrane.
What is the composition of the plasma membrane?
The plasma membrane is composed of a phospholipid bilayer with integral proteins. The lipid bilayer consists of a polar head and a non-polar tail.