Biological membrane

Biological Membrane

A Biological Membrane or Biomembrane is an enclosing or separating membrane that acts as a selectively permeable barrier within living things. Biological membranes, in the form of eukaryotic cell membranes, consist of a phospholipid bilayer with embedded, integral and peripheral proteins used in communication and transportation of chemicals and ions. The bulk of lipid in a cell membrane provides a fluid matrix for proteins to rotate and laterally diffuse for physiological functioning. Proteins are adapted to high membrane fluidity environment of lipid bilayer with the presence of an annular lipid shell, consisting of lipid molecules bound tightly to surface of integral membrane proteins.

Structure

The structure of a biological membrane is composed of a lipid bilayer, which is a double layer of lipids (fats). The lipid bilayer is the barrier that keeps ions, proteins and other molecules where they are needed and prevents them from diffusing into areas where they should not be. Lipid bilayers are ideally suited to this role because, even though they are only a few nanometers in width, they are impermeable to most water-soluble (hydrophilic) molecules. Bilayer permeability is one of the main ways cells control what enters and exits.

Function

Biological membranes have three primary functions: (1) they keep toxic substances out of the cell; (2) they contain receptors and channels that allow specific molecules, such as ions, nutrients, wastes, and metabolic products, that mediate cellular and extracellular activities to enter or exit the cell; (3) they separate vital but incompatible metabolic processes conducted within organelles.

Types of Biological Membranes

There are several types of biological membranes that can be found within the body, including the Cell Membrane, Mitochondrial Membranes, Endoplasmic Reticulum, Golgi Apparatus, Nuclear Membrane, and Lysosomal Membrane.

See Also

• Cell Biology
• Molecular Biology
• Biochemistry

References

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  Phospholipids aqueous solution structures
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  Lipid bilayer with various components