Chapter 8 



BIOCHEMICALLY IMPORTANT MINERAL 



ELEMENTS 



Definition 



The mineral elements of biochemical interest are all those chemical 

 elements, except carbon, hydrogen, oxygen, and nitrogen, which are, or 

 may be, present in the tissues of living organisms. They are frequently 

 called inorganic, or ash elements, since, as a rule, they remain in the 

 ash when biological materials are burned. Those which have been 

 proved to be essential constituents of living tissues are listed below. 

 They are classified as major and minor (or trace) elements on the basis 

 of the amounts usually present in biological samples. 



Most of these elements are required by living organisms, generally. 

 However, boron is needed only by plants; sodium, chlorine, iodine, and 

 cobalt, only by animals. Thus plants require 15 chemical elements in 

 all (counting C, H, 0, and N), and animals 18. 



Aluminum, vanadium, arsenic, bromine, fluorine, silicon, and other 

 mineral elements are widely distributed in living cells and may have 

 important biological functions, but as yet their essential nature has not 

 been demonstrated, except in a few isolated cases {e.g., vanadium is 

 apparently a normal, necessary constituent of a respiratory pigment in 



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