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Nucleotide Biosynthesis

1. Purine Biosynthesis (see page 271)
   1. The General Pathway from glucose to inosinic acid.
      (Note the requirement of the vitamin, FH₄.)

      
      Notes: the bicyclic rings = pterin; "*" indicates active centers; PABA is a vitamin for many creatures but not chordates.
      Folic Acid (FH4 or THFA: pterolyl-tri-L-glutamate) (see page 270)
      
      
      
      

   2. Adenylic acid (requires GTP)
      
      
      
      

   3. Guanylic acid (requires ATP)
      
      
      
      

2. Pyrimidine Biosynthesis (see page 272)
   1. General Pathway from the Krebs Cycle and the Urea Cycle to UTP
      
      
      
      

   2. Cytidylic acid and CTP
      
      
      
      

   3. TTP (see below since it is a deoxyribonucleotide)

3. DEOXYribonucleotide Biosynthesis
   1. Reduction of the 2'-position in the ribonucleotide
      

      CMP

      CDP

      dCDP

      dUMP

      TMP

      TDP

      TTP

   2. The methylation of dUMP to form the thymine ring.