Consider two n-linked oligosaccharide chains on the same protein. the first chain contains three mannose residues and three negatively charged sialic acid residues, as well as other residues. the second chain contains only two n-acetylglucosamine and eight mannose residues. which chain seems to have been added to the protein such that it is not fully accessible to the processing enzymes in the golgi apparatus? which chain is endo h-sensitive?