Structure and Composition of Cell Membrane
Despite differences in structure and function, all living cells in multicellular organisms are surrounded by a cell membrane. Just like the outer layer of the skin separates the body from its environment similarly, the cell membrane, also known as 'plasma membrane,' separates the inner content from its exterior environment.
Cell Membrane
The cell membrane is known by different names like plasma membrane or cytoplasmic membrane, or biological membrane. The term "cell membrane" was first introduced by C. Nageli and C. Cramer in the year 1855. Later on, in 1931, the term "plasmalemma" for cell membrane was given by J. Plowe. The cell membrane separates the cell's internal environment from the extracellular space. This separation allows the protection of cells from their environment.
Prokaryotes vs Eukaryotes
The cell is defined as the basic structural and functional unit of life. The cell membrane bounds it. It is capable of independent existence.
Plasma membrane is the external boundary of the cell that protects the cell from the exterior environment. Plasma membrane is selectively permeable membrane and allow only specific molecules to pass through. Plasma membrane is composed of lipid bilayer having hydrophilic head interacts with the aqueous environment of exoplasmic surface and cytosol and hydrophobic tail present in the core, integral and peripheral membrane proteins, carbohydrates and cholesterol. Carbohydrates moiety associated with lipid termed as glycolipid present only in the layer faces at the exoplasmic side. Components present of the plasma membrane also act as a ion channels, receptors, transporters, helps in signaling processes and also provide cell to cell adhesion.
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