What is the name of the structural polysaccharide containing nitrogen, found in the exoskeleton of insects?

The structural polysaccharide found in the exoskeleton of insects is known as chitin. Chitin is a biopolymer made up of N-acetylglucosamine units, which include nitrogen in their structure. This nitrogen presence distinguishes chitin from other polysaccharides like cellulose and starch, which do not contain nitrogen in their sugar units.

Chitin provides not only structural support to the exoskeletons of insects, but also adds to the rigidity and strength necessary for protection and shape maintenance. This polysaccharide is also found in the cell walls of fungi and the shells of some crustaceans, further underscoring its role in biological structures across various organisms.

In contrast, cellulose is a polysaccharide that serves as a structural component in the cell walls of plants but is strictly composed of glucose units without nitrogen. Starch is primarily a storage polysaccharide made up of glucose, used by plants for energy storage. Keratin, while a structural protein found in hair, nails, and animal horns, is not a polysaccharide and therefore does not fit the description of a structural polysaccharide containing nitrogen.