The glycocalyx or glycocalyx is an outer shell of the plasma membrane present in animal cells and some protozoa.
Glycocalyx consists of a 10 to 20 nm thick protein-linked sugar coating that surrounds the cell and gives it protection. This coverage is constantly renewed by the cells.
The term glycocalyx is derived from the Greek glykys, sugar, and from latin calyx, bark.
It is common for cells to have envelopes outside the plasma membrane that have specific functions. The main envelopes are the glycocalyx and the cell wall. The cell wall is found in plant cells, bacteria and fungi.
Composition of Glycocalyx
Glycocalyx is composed of glycolipids (carbohydrates associated with lipids) and glycoproteins (carbohydrates associated with proteins), produced and renewed by the cell itself.
Glycocalyx Functions
Among the functions of glycocalyx are:
Mechanical protectionand against chemical and physical aggression. For example, glycocalyx from intestinal mucosal cells protect against the effects of digestive enzymes.
Glycocalyx confers a specific microenvironment to the cell. As it constitutes a kind of mesh that surrounds the cells, it retains substances that can alter natural conditions of acidity and salinity.
One example is the glycocalyx in kidney cells, which acts as a filter, selecting substances that enter the cell.
Cell recognition, the same cells have the same composition in the glycocalyx, which allows them to recognize each other. This also favors the adhesion between cells.
The oligosaccharides (union of two to ten monosaccharides) present in the glycocalyx of the red blood cells determine the blood groups of the ABO system.
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cell wall
Plasma membrane