OF THE 



UNIVERSITY 



OF 



CHAPTER II. 



CARBOHYDRATES. 



THE name carbohydrates is given to a class of bodies which are 

 an especially prominent constituent of plants and which are found 

 also in the animal body either free or as an integral part of various 

 proteins. They are called carbohydrates because they contain the 

 elements C, H and O ; the H and O being present in the proportion 

 to form water. The term is not strictly appropriate inasmuch as 

 there are bodies such as acetic acid, lactic acid and inosite which 

 have H and O present in the proportion to form water, but which 

 are not carbohydrates, and there are also true carbohydrates which 

 do not have H and O present in this proportion, e. g., rhamnose, 

 C 6 H 12 O 5 . 



Chemically considered, the carbohydrates are aldehyde or ketone 

 derivatives of complex alcohols. Treated from this standpoint the 

 aldehyde derivatives are spoken of as aldoses, and the ketone deriva- 

 tives are spoken of as ketoses. The carbohydrates are also fre- 

 quently named according to the number of oxygen atoms present in 

 the molecule, e. g., trioses, pentoses and hexoses. 



The more common carbohydrates may be classified as follows : 



I. Monosaccharides. 



1. Hexoses, C G H 12 O . 



(a) Dextrose. 



(b) Laevulose. 



(c) Galactose. - 



2. Pentoses, C 5 H 10 O 5 . 



(a) Arabinose. 3 



(b) Xylose. 



(c) Rhamnose (Methyl-pentose), C 6 H 12 O 5 . 

 II. Disaccharides, C 12 H22O n . 



1. Maltose. 



2. Lactose. ' 



3. Iso-Maltose. 



4. Sucrose. 



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