182 INTERMEDIATE METABOLISM 



These on hydrolysis yield two molecules of a mono- 

 saccharide according to the equation — ■ 



C12H22O11 + HgO = 2C6Hi20g. 



Cane sugar yields glucose and Isevulose. 



Maltose yields two molecules of glucose. 



Lactose yields glucose and galactose. 



All the above sugars except laevulose are dextro-rotatory. 



C. Polysaccharides (CgHjoOg). 



These are substances of very high molecular weight. 

 They include starch, inuhn, cellulose, glycogen and dextrins. 



There exists also another series of sugars built up on a 

 j&ve-carbon-atom basis : — 



Pentoses (CgH^oOg). 



Pentosans (C5H8O4) are the corresponding poly- 

 saccharides. They occur in vegetable foods. 



Digestion of Carbohydrates 



During digestion polysaccharides and disaccharides are 

 converted into monosaccharides, the change in the case 

 of starch occurring in the following stages, recognisable 

 by the reaction with iodine : — ■ 



Starch 



