Question

Describe the structure of a glycogen molecule. What is the advantage of its branched structure?

Short answer

Glycogen is a glucose branched polymer. Glucose residues are linked linearly by -1,4 glycosidic bonds, and a chain of glucose residues branches off every ten residues via -1,6 glycosidic linkages.

The branched structure of glycogen facilitates glucose mobilization.

Step-by-step solution

Structure of Glycogen

When studied, glycogen molecules were found to have spherical intracellular granules and have a diameter of 100- to 400-Å. They have a branched structure and each contains up to 120,000 units of glucose.

Glycogen has one reducing end and also a non-reducing end which is seen at each branching.

It is a polymer of glucose molecules of a specific manner, i.e. α(1→4)-linked D-glucose with α(1→6)-linked branches every 8–14 residues.

Advantage of branched structure

Glycogen also has a non-reducing end at the branch from where glucose is removed for mobilization by releasing glucose units. This process can be done more easily only because of the branching structure of glycogen.