Carbohydrates are biological molecules composed of carbon, hydrogen and oxygen, hence the name, carbo- (carbon) -hydr- (hydrogen) -ate (oxygen). Generally speaking (a notable exception being deoxyribose), for every 1 carbon atom, they have 1 oxygen atom and 2 hydrogen atoms. The chemical names for carbohydrates end with –ose.

Carbohydrates are perhaps best known for being an energy source. Everyone knows about "complex" carbohydrates like those found in whole grains, and "simple" carbohydrates like those is sugar sweetened foods, but carbohydrates have other roles in biological systems. Some proteins have carbohydrates physically attached to them as part of their quaternary structure, to create glycoproteins. Carbohydrates are also an essential component of nucleic acids, being the ribose and deoxyribose components of RNA and DNA respectively. Cellulose is a carbohydrate that forms the strong cell wall of plant cells.

Carbohydrates can form polymers. Individual carbohydrate molecules are called monosaccharides, and can form bonds (releasing a molecule of water in the process) with other carbohydrate molecules, forming disaccharides, and even longer chains. This is where the basis for different dietary carbohydrates come from. What are in dietary terms called sugars are mono- or disaccharides, while "complex carbohydrates" are longer chains of carbohydrates, which take longer to break down.

Carbohydrates are easy to metabolize into energy, which makes them a favourite source of energy, and a storage medium, in lots of life forms. Carbohydrates are metabolized by the process of respiration (not to be confused with breathing, which is ventilation), which converts the carbohydrates into carbon dioxide and water, and generates ATP.

All in all carbohydrates are quite interesting!

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