Discovery Science: Carbon – Carbohydrates: the World of Sugars

Earth Science: Carbon – Carbohydrates: the World of Sugars

In our culture sugar belongs to the essential staple foods. Chemically, the category of sugars consists of sweet-tasting organic compounds of carbon, oxygen, and hydrogen.

Sugars are also referred to as hydrates of carbon, or carbohydrates. These hydrates are compounds that are bonded to water by electrostatic forces. Chemically, sugars are polyvalent alcohols, since sugar molecules contain one or several hydroxyl groups. The simplest carbohydrate is glycoaldehyde. The most important natural sugars are pentose and hexose sugars.

These include ribose, glucose, and fructose. These sugars are made up of a single sugar molecule, and therefore called monosaccharides. However, this group was named after saccharose, that is made up of two sugar molecules: glucose and fructose. It, like lactose (milk sugar, made up of glucose and galactose), is a disaccharide. Apart from monosaccharides and disaccharides, there are also polysaccharides that consist of many thousands of sugar molecules.

The best known example is starch, which serves as energy storage for plants such as potatoes and corn (maize). The photosynthetic activities of plants produce glucose and bond up to a thousand glucose molecules together into large, branched structures that are stored in the form of starch grains. Cellulose, a component in the cell walls of plants, is also a polysaccharide made up of glucose units.

Next to their roles as a supplier and store of energy, many carbohydrates also serve as structural elements. The element that most frequently occurs in the human body is ribose. After giving off one oxygen atom (deoxidation), it is used in the human genome as deoxyribo-nucleic acid (DNA). Also, one finds oxyribo-nucleic acid (RNA) functioning as amino acid carriers and information messengers in protein biosynthesis (messenger RNA), as well as in ribosomes.

Nearly all cells of the human body have carbo- hydrates and their derivatives on their surface areas. The best example is the structures on red blood cells. Most tissue cells have sugar molecules, so that certain cells of the immune system can distinguish between the one’s own tissue and foreign tissue.


German chemist Emil Hermann Fischer (1852-1919) discovered the spatial structure of saccharides and the chemistry of carbohydrates. He received the Nobel Prize in chemistry in 1902 for his work on carbohydrates.

After getting cancer, probably resulting from his work with toxic phenyl hydrazine, one of his discoveries, Fischer took his own life in 1919.