The Differences Between Monosaccharides & Polysaccharides

By Jess Kroll
Simple carbohydrates, like those contained in powdered sugar, are quickly broken down into energy.
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Carbohydrates, which are chemical compounds consisting of carbon, hydrogen and oxygen, are one of the primary sources of energy for organic life. Also known as saccharides, or more commonly as sugars, carbohydrates are often subcategorized by their chemical structure and complexity into three different types: monosaccharides, disaccharides and polysaccharides. Each of these compounds have their own distinct structure and purpose within biochemistry.


Monosaccharides are the most simple of carbohydrate compounds, consisting of only one chemical ring. Monosacchrides themselves are further divided into aldoses and ketoses, as well as different types on monosaccharides depending on the number of carbon atoms present in the chemical ring. Because there is only one ring in the molecule monosaccharides are quickly broken down and provide an immediate and short feeling of energy. The name itself, with the prefix "mono," refers to the fact that there is only one saccharide ring present.


One step higher in the complexity of sugars, disaccharides consist of two chemical rings. The individual monosaccharides are joined by an oxygen atom, a weaker bond than those used to hold the individual monosaccharides together, thus making each ring easy to break apart. Disaccharides can consist of either two of the same monosaccharides, such as maltose (two glucose monomers), or two different monosaccharides, such as lactose (one galactose and one glucose). The dual rings make disaccharides slower to break down than monosaccharides. Again, the prefix "di" refers directly to the fact that there are two chemical rings in the molecule.


Polysaccharides are chains of monosaccharides, again bonded by oxygen molecules, with more than three chemical rings. The prefix "poly" refers to many, meaning that polysaccharides can have any number of individual sacchardies, from three to ten thousand, contained within its chain. As well, some polysaccharides consist of only one type of monosaccharide, while others consist of several different types. Since polysaccharides include many bonded monosaccharides, they are the slowest type of carbohydrate to be broken down.


The speed at which a saccharide is broken dictates how the stored energy is released. Since monosaccharides are the simplest of the compounds, with only one chemical ring, they produce the immediate effect. But since they are so simple they also offer the least energy. The effect is like the sugar rush found after eating candy or other foods with a high simple sugar content. Polysaccharides are slower to completely break down, but also offer the great long-term energy boost. This is why starch, a type of polysaccharide, is often recommended for people who require a long-term energy boost. Hence the term "carbo loading" for long-distance runners.