The Chemistry of Carbohydrates

Carbohydrates, or more commonly referred to as sugars are a combination of carbon (C) and water (H2O) molecules.  The general chemical combination of carbohydrates is (CH2O)n, where n is the number of carbon atoms and may range from 3 to 7, or for the chemical formulas, C3H6O3 to C7H14O7.   Differences in the bonding sites (linkages) of the water molecule to the carbon atom change the biochemical characteristics of the molecule.  The most commonly discussed carbohydrates that are of interest in Sports and Nutrition are the carbohydrates with 5 or 6 carbon atoms, or C5H10O5 and C6H12O6.  To help understand the the differences in the biochemical nature that is derived from linkages of the water molecules to the atom, we only need to look at some well known simple sugars.  Glucose, Fructose and Galactose all have the same chemical formula (C6H12O6); however, because the water molecules are linked to the carbon atoms in a slightly different formation, each of these sugars have uniquely different biochemical characteristics.

Types of Carbohydrates

There four categories of carbohydrates, and they differ in the NUMBER of simple sugars linked in a molecule.  The four categories of carbohydrates are monosaccharides, disaccharides, oligosaccharides, and polysaccharides.  To further differentiate between these sugars we use the Greek suffix "ose" (which means sugar) in combination with the number of carbon atoms in the simple sugar to develop subgroupings within each carbohydrate category.  The groupings of these categories and sub categories are as follows:

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Monosaccharides and Disaccharides

Of these different categories of sugars, the monosaccharides (hexoses), disaccharides and polysaccharides (hexosans) are of interest to this class for the discussion of energy transfer.  The monosaccharides are our simple sugars, and GLUCOSE is the key ingredient in energy metabolism of the human body.  Note that in the disaccharide category, Lactose is the combination of  GLUCOSE+Galactose, Sucrose is the combination of GLUCOSE+Fructose, and Maltose is the combination of Glucose+Glucose.  


Polysaccharides can be divided into two groups: PLANT polysaccharides and ANIMAL polysaccharides.  The two common forms of PLANT polysaccharides are STARCH and FIBER.   These polysaccharides are known as the COMPLEX CARBOHYDRATES.  The ANIMAL polysaccharide that is most common in human food consumption is GLYCOGEN.   Glycogen is stored in animal muscle tissue (MEAT) and organ tissue (LIVER).

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