The biological importance of sugar is that it provides the body with immediate energy, but it also provides a source for stored energy. While sugar is often blamed for being unhealthy, the body is unable to function correctly without it.
Table sugar, also known as sucrose, is the main way that sugar finds its way into the human diet. This sugar is made up of one molecule of glucose and one molecule of fructose. Since the body is unable to absorb sucrose in its raw form, it has to break down the chemical link that joins glucose and fructose together. Once the bond is broken, the body absorbs the molecules and transports them to the liver for distribution and processing.
When the liver distributes glucose, insulin hormones facilitate its transfer into cells. Here, the glucose is metabolized by the cells and used for immediate energy. If the body has an excess of glucose that is not needed for immediate energy, it's turned into a new compound called glycogen. The process of creating glycogen is called glycogenesis, and the liver creates chains of glycogen through a chemical bond. When the body is in need of energy, the body breaks these bonds and turns the glycogen into glucose.