Question

Glycogen and protein are both polymers. Explain why there can only be one type of glycogen molecule, but there can be many types of protein molecule.

Answer 1

glycogen is composed of chains of glucose molecules hooked together alpha 1,4 and branched as alpha , 1,6. This allows for only weakly branched or highly branched glycogen with the same ONE type of molecule present, glucose . Proteins , on the other hand are composed of chains and cross-linked chains of amino acids of which there are 20 naturally occurring AAs with quite different properties. You can see immediately the tremendous number of different combinations of 20 AAs that are possible. In glycogen, the position of a glucose molecule makes no difference because one glucose is like any other...In proteins substituting one amino acid for a different amino acid at a particular position will change the properties of the protein sometimes minutely other times drastically ( such as the single AA substitution of valine for a glutamic acid in a hemoglobin beta chain converts normal hemnoglobin to sickle cell hemoglobin )
just google it 'u'll get the answer:)