Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
The cytoplasmic membrane, also known as the plasma membrane, is a selectively permeable barrier that surrounds the cytoplasm of a cell. It plays a critical role in controlling the movement of substances in and out of the cell.
5 Must Know Facts For Your Next Test
The cytoplasmic membrane consists primarily of a phospholipid bilayer with embedded proteins.
It is responsible for maintaining the cell's internal environment by regulating ion and molecule passage.
In prokaryotic cells, it is involved in energy production through processes like respiration and photosynthesis.
The fluid mosaic model describes its structure, highlighting the flexibility and dynamic nature of the membrane.
It contains specific transport systems such as channels, carriers, and pumps to facilitate nutrient uptake and waste removal.
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Related terms
Phospholipid Bilayer: A double layer of phospholipids that forms the core structure of cellular membranes.
Selective Permeability: The ability of a cell membrane to allow certain molecules or ions to pass through while blocking others.
Fluid Mosaic Model: A model that describes the dynamic and flexible nature of biological membranes composed of lipids and proteins.