Nutrition, Diet and Body Weight Quiz

See Carbohydrates. Option C is correct. Glycogen is the main storage form of carbohydrate in animals. It is a polysaccharide (a long chain made of many sugar units) built entirely from glucose and is highly branched, much like a bush, rather than being one long straight chain. It is stored mainly in the liver and in skeletal muscle. When blood glucose falls, the liver breaks glycogen down to release glucose into the blood, a process called glycogenolysis. This matters clinically because glycogen is the body's readily available store of glucose, so it helps to keep the blood glucose steady between meals. The plant equivalent is starch, which is why glycogen is sometimes called animal starch. Remember that a polysaccharide is a polymer (a large molecule built from repeating units), whereas the other sugars in the list are much smaller.

• Glycogen: the main storage form of carbohydrate in animals.
• Structure: a highly branched polysaccharide built entirely from glucose.
• Stores: mainly the liver and skeletal muscle.
• Liver role: breaks glycogen down to release glucose when blood glucose falls.

A quick way to remember the pairs is that plants store starch and animals store glycogen, and a name ending in -ose with only two units, such as sucrose, lactose or maltose, is a sugar and not a store.