How is it possible that the codons GUU, GUC and GUA all code for valine, but that only one charged tRNA molecule (with one specific anticodon sequence) is involved in the translation process?
When we say the genetic code is degenerate, it means that more than one codon can specify the same amino acid. For example, GUU, GUC and GUA all code for valine. In general, the genetic code is nearly universal, because it is used in the same way by viruses, prokaryotes, fungi, plants, and animals. there are a few exceptions, which occur primarily in protists and yeast and mammalian mitochondria.
The sequence of valin anticodons in tRNA directly recognizes codon sequences in mRNA, with some room for wobble (at 3rd nt) so only one transfer RNA is required.
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