Glycosidic bond

A glycosidic bond is formed between a hemiacetal group of a sugar molecule (such as glucose) and an alcohol functional group to form an acetal.

A N-glycosidic bond is formed between the hemiacetal group of a sugar molecule (such as ribose) and a N-H group on an aromatic ring. An example of this is the bond between a nitrogenous base and the deoxyribose molecule in DNA.

A-glycosidic bonds can also connect two monosaccharides, such as the linkage of glucose and fructose to create sucrose. It is simply the dehydration reaction between the hydroxide on the right edge of one sugar to the hydroxide on the left edge of the other sugar. A water molecule is extracted (causing a dehydration reaction), and a bond is formed, leaving an oxygen atom between the two monosaccharides, and creating a disaccharide.