Anticodon Pairing and Wobble

A codon forms base pairs with a complementary anticodon of a tRNA when an amino acid is incorporated during protein synthesis. Because there are 64 possible codons, one might expect to find 64 types of tRNA but, in fact, the number is less than 64 in all cells. 

If there are 64 codons, how can there be less than 64 tRNA molecules  

A universal code is one that is the same in all organisms. The universality of the code has been observed in viruses, prokaryotes, and eukaryotes. However, there are some exceptions. Some codons seen in mitochondria are different 

Note that there are no variations in base pairing when the wobble position is occupied by A or C. 

The genetic code is based on a series of three bases coding for an amino acid. 

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