Monosaccharides, the simplest form of carbohydrates, can be linked together to form disaccharides through a process known as dehydration synthesis, also referred to as a condensation reaction.

In more detail, monosaccharides can combine to create more complex sugars, such as disaccharides. This process involves the removal of a water molecule, which is why it is termed ‘dehydration synthesis.’ It is also called a condensation reaction because water ($H_2O$) is generated as a by-product of the reaction.

The reaction occurs between two monosaccharides, with each contributing a component of the water molecule that will be eliminated. One monosaccharide provides a hydroxyl group ($-OH$), while the other contributes a hydrogen atom ($H$). When these two components combine, they form a water molecule, which is subsequently released. The remaining portions of the monosaccharides then bond together, resulting in the formation of a disaccharide.

The bond that links the two sugar molecules is known as a glycosidic bond. This type of bond is a covalent bond, which involves the sharing of electrons between atoms. The formation of a glycosidic bond is crucial, as it connects the two monosaccharides to create a disaccharide.

A classic example of this process is the formation of sucrose, a common disaccharide. Sucrose is generated through the condensation of a glucose molecule and a fructose molecule. During this reaction, the glucose molecule donates a hydroxyl group, while the fructose molecule donates a hydrogen atom. These combine to produce water, which is released, and the remaining parts of the glucose and fructose molecules bond together to form sucrose.

This dehydration synthesis process is not limited to the formation of disaccharides; it also plays a vital role in the creation of polysaccharides, which are complex carbohydrates. Polysaccharides consist of long chains of monosaccharides linked together by glycosidic bonds. The same dehydration synthesis mechanism occurs repeatedly to connect multiple monosaccharides, resulting in these larger carbohydrate structures.