The basic building blocks of carbohydrates are simple sugars known scientifically as monosaccharides. A monosaccharide is a simple sugar molecule containing between three and seven carbon atoms. These simple sugars act as chemical monomers, which are single units that can join together.
Monosaccharides link together through a condensation reaction to form strong connections called glycosidic bonds. This specific linking process creates disaccharides, oligosaccharides, and massive chains known as polysaccharides. A polysaccharide is a very large polymer chain constructed from many simple sugar molecules.
In water, dissolved carbohydrates constantly shift between open-chain structures and closed ring shapes. The closed ring shapes are much more stable and prevalent in bodily fluids. Glucose is the most important monosaccharide for life and the main sugar circulating in blood.
Cells use glucose to perform cellular respiration and generate vital ATP energy. Large polysaccharides serve two entirely different, yet equally important, roles in the natural world. First, they act as highly compact energy storage materials for future biological use.
Plants store extra energy as starch, while animals store it in the form of glycogen. Second, massive polysaccharides provide rigid structural support for both plants and animals. Plants use a tough carbohydrate called cellulose, while insects build their hard shells from chitin. Carbohydrates also form unique three-dimensional shapes that help cells recognize each other during biological processes.