Detail 1: Code Degeneracy 1 Often, when the first two nucleotides are identical the third nucleotide can be either C or U without changing the code. A and G at the third position are interchangeable as well 2. Transition in the third position of a codon specifies a same amino acid. Transversion in this position changes the amino acid about half the timeDetail 1: Code Degeneracy 1. Often, when the first two nucleotides are identical, the third nucleotide can be either C or U without changing the code. A and G at the third position are interchangeable as well. 2. Transition in the third position of a codon specifies a same amino acid. Transversion in this position changes the amino acid about half the time