MACROMOLECULES 85 



protein, has succeeded in recombining them to reform the macromolecule 

 of tobacco mosaic virus), so that it is not possible to say that any macro- 

 molecule in the biosphere is known in all its details. Nevertheless, the 

 study of synthetic polymers has greatly aided the understanding of natural 

 polymers. 



I. POLYSACCHARIDES 



Polysaccharides are very widely distributed in the biosphere, being 

 employed as a structural material (cellulose, xylan, chitin, etc.) and as a 

 form for storing the monomers (starch, glycogen, inulin, galactogen, etc.). 



The polysaccharide molecule is formed by the association, by means of 

 oside bonds, of a large number («) of sugar molecules. The uronic acids 

 are associated into polyuronides in the same way as the sugars form 

 polysaccharides. 



«(CeHi,Oe) - n H,o = (CeH,oO> 



D-glucose cellulose 



D-mannuronic acid 

 A. HOLOPOLYSACCHARIDES 



[a) Polysugars or Polyoses 

 1. Hexosans 



(a) Cellulose — The name "cellulose" is given to mixtures of homologous 

 polymers which give a quantitative yield of D-glucopyranose when hydro- 

 lysed in strong acid. Cellulose is the most abundant structural material in 

 plants. It is also found in many bacteria and even in certain groups of 

 animals, such as the Tunicates. 



Cellulose is present in the pure state in the hairs of the cottonseed. 

 Complete acid hydrolysis of cellulose by strong, concentrated mineral acids 

 gives D-glucopyranose in quantitative amounts. Careful partial hydrolysis 

 in the presence of acetic anhydride and sulphuric acid (acetolysis) gives 

 molecules of cellobiose (4-D-glucopyranose-/3-D-glucopyranoside) and tri- 

 saccharides which can be hydrolysed by the enzyme emulsin. Hence, it 



REFERENCES 



Frey-Wyssling, a. 1957. Macromolecules in Cell Structure. Harvard University 



Press, Cambridge, Mass., U.S.A. 

 Meyer, K. H. (1942). Natural and Synthetic High Polymers. Interscience, New York. 

 Staudinger, H. (1947). Makromolekulare Chemie und Biologie. Wepf, Bale. 



