266 



UNITY AND DIVERSITY IN BIOCHEMISTRY 



enzyme catalyzing the activation of a particular amino acid in the presence 

 of ATP, with the formation of an amino acid-AMP-anhydride, also 

 catalyzes the fixation of this compound on a short, soluble piece of RNA 

 chain. This carrier brings the amino acid on to the complementary sequence 

 of the template. By this mechanism, the long code represented by numerous 

 genes on a DNA chain, copied on RNA chains, controls the biosynthesis 

 of a number of proteins, among which are numerous enzymes controlling 

 the specific metabolism of the cell. 



Ci 



CO. 



purines 



oxalosuccinic acid 

 oxaloacetic acid 

 arginine (guanidine C) 

 glucose (C — 3 and 4) 



histidine (C — 1 and 5) 



t 

 pentoses < v 



oxaloacetate 



-►-pyrimidines 



methionine (C — 1 and 4) 



desoxypentoses -^- 



phosphoglyceraldehyde 



aspartic->-homoserine 



acid 



isoleucine (C — 3 and 4) 

 valine (C— 3 and 4') 



threonine 



cysteine 



\. 



serine-^ — glycine-*' 

 cystine 



pyruvic acid 



/ 



a-aminobutyric 

 acid 



isoleucine 

 (C— 1,2,5 and 6) 



alanine 

 tr>-ptophan side 

 -chain valine (C — 1,2 and 4) 



leucine (C — 3,4,5 and 5') 



succinyl-CoA 



a-ketoglutarate 



steroids, leucine (C — 1 and 2) 

 carotenoids, lysine (C — 1 and 2) 

 terpenes, oxaloacetic acid, fatty acid 



-►-porphyrins 

 lysine 



-glutamic acid 



lysine (C — 3 and 6) 



proline 



sedoheptulose 



i 



i. 



hydroxyproline 



benzene ring of 

 amino acids 



Fig. 81 — Utilization of various key-materials for biosynthesis. 



