BIOLOGICAL ORDER 



bases, each bound to a sugar to form a nucleoside. A molecule of 

 phosphoric acid is attached to each sugar, thus forming a nucleotide. 

 The nucleotides are united by phosphodiester bonds, thus forming a 

 long chain (Figure 1). 



The analysis of proteins reveals that they are composed of twenty 

 amino acids. An amino acid is, as indicated by its name, an aminated 

 acid. Glycine, for example, is aminated acetic acid. In proteins, 



H H 

 "■ " C^ \ C— C — C — COOH N c 



\./ 



I.I 



H NH2 



H H 



/ \ I II II n iMn2 n I I 



/ \ C. ^C. C NC^ C C— C— COOH 



H H NHg 



glycine tryptophan histidine 



c c^ c;' 



H+N C — N^ C — N C- 



' II H II H II 







peptide chain 



Figure 2. Three Amino Acids, General Scheme of a Free Amino 

 Acid, Scheme of a Peptide Chain. 



amino acids are assembled by a peptide bond. The a-amino groups 

 of one amino acid are joined to the carboxyl group of another. A 

 protein is a chain of amino acids (Figure 2). 



The nucleic bases and the amino acids are found in all living 

 beings. No proteins can be synthesized if even one amino acid is 

 missing. No nucleic acid can be produced if even one base is missing. 

 These necessary cogs of living beings have therefore been called 

 "fundamental constituents" or "essential metabolites." 



Thus the microorganism is a complex system built of a few 

 building blocks assembled into specific macromolecules. Each macro- 



[12] 



