Why might it be advantageous for a storage polysaccharide to

Why might it be advantageous for a storage polysaccharide to have a branched-chain structure instead of a linear structure?

Solution

The polysaccharides has two major function i.e. storage of energy and structure formation of cells. The monosaccharides are stored in the form of polysaccharides in the cells to help lower the osmotic pressure within the cells. The polysaccharides for food storage are majorly branched in nature. One reason for branching is that branched molecule has larger average molecular mass, thus helping reduce osmotic pressure more effectively than linear molecules. The major reason is branched chain polysaccharides are digested rapidly. Since digestive enzymes works from the end (exolytically) and thus more ends leads to maximum accessibility on need for energy. The enzyme glycogen phosphorylase which cleaves one glucose molecule at a time from a non-reducing end, can now work simultaneously in multiple ends. Branching structure is an efficient way of since it is compact and coiled, and increasing accessibility of each glucose molecule.

On the other hand a linear structure is better suited for providing rigidity and firmness to cell wall by forming hydrogen bonds with parallell linear chains.