The primary function of carbohydrates attached to the exterior of cell membranes is cell identification and recognition. These carbohydrates form distinctive molecular "ID badges" that allow cells to recognize one another, which is crucial for processes such as immune response and cell communication. They are involved in cell-cell recognition, adhesion, and signaling, helping the immune system distinguish between self and non-self cells. This function is exemplified by blood group antigens on red blood cells, which are carbohydrate markers that determine blood type. Additionally, these carbohydrates can act as binding sites for pathogens and play roles in development and cellular interactions
. In summary, carbohydrates on the cell membrane exterior primarily serve as identification molecules that enable cells to recognize and interact with each other and their environment.
