How are polysaccharides formed from monosaccharides?

Polysaccharides are formed from monosaccharides through a process called dehydration synthesis or condensation reaction.

In more detail, polysaccharides are complex carbohydrates that are made up of more than two monosaccharides, which are simple sugars. The process that links these monosaccharides together is known as dehydration synthesis, also referred to as a condensation reaction. This is because a molecule of water (H2O) is produced, or 'condensed out', during the reaction.

The process begins when two monosaccharides come into close proximity. Each monosaccharide has a hydroxyl group (-OH) and a hydrogen atom (-H) that are attracted to each other. When they come together, the hydrogen atom from one monosaccharide and the hydroxyl group from the other monosaccharide combine to form a molecule of water. This leaves behind a bond between the two monosaccharides, creating a disaccharide.

This process can continue, adding more monosaccharides to the chain, to form a polysaccharide. Each time a monosaccharide is added, a molecule of water is produced. This is why the process is called dehydration synthesis, as water is being removed each time a bond is formed.

The bonds that are formed during this process are known as glycosidic bonds. These bonds are covalent, meaning they involve the sharing of electrons between atoms. This makes them very strong and stable, which is why polysaccharides can be large and complex molecules.

Different polysaccharides can be formed depending on the types of monosaccharides used and the way they are linked together. For example, starch and cellulose are both polysaccharides made from glucose monosaccharides, but they have different structures and properties because the glucose units are linked together in different ways.

In summary, the formation of polysaccharides from monosaccharides involves a dehydration synthesis or condensation reaction, where a molecule of water is produced and a glycosidic bond is formed each time a monosaccharide is added to the chain.