The Emerging View of Carbohydrate Structure

In those eukaryotes which have been studied in some detail (i.e. those which are multicellular organisms) the opposite pressures may act. If complex saccharides are involved in cell adhesion, recognition or some other social process, there may be strong pressures to conserve structures, or to vary them only gradually and within strict rules. Indeed, many types of saccharide sequence do seem to be stongly conserved, but there is insufficient information about primitive eukaryotes to test whether this also applies to them. 

There is little evidence to suggest a close evolutionary relationship between bacterial and eukaryotic saccharides, though they are clearly either remote cousins, or, possibly, the result of a remarkable degree of evolutionary convergence. Until much more is known of primitive eukaryotes and the more obscure members of the prokaryotes no very firm analogies can, or should, be drawn. 

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