Final answer:
Leucine is encoded by the largest number of codons (six), while methionine is encoded by only one codon (AUG), which also functions as the initiation codon. The genetic code is degenerate, except for methionine and tryptophan, meaning that each amino acid can be encoded by multiple codons.
Step-by-step explanation:
The amino acid encoded by the largest number of codons is leucine. In the genetic code, leucine is specified by six different codons. On the contrary, methionine is unique because not only is it specified by a single codon (AUG), which is the least number of codons for an amino acid, but this codon also serves as the initiation codon for protein synthesis. It is important to note that tyrosine, thymine, and methionine are other amino acids, but they are not encoded by a larger number of codons than leucine. Regarding the information provided, it takes three 'letters' or nucleotides of RNA to code for a single amino acid, which answers another query mentioned.
When it comes to the genetic code, it's notable that each codon consists of three nucleotides and that the code is both degenerate and universal. Degenerate means that except for tryptophan and methionine, each amino acid is encoded by more than one codon. The universal aspect indicates that these codons are recognized in the same way across all living organisms, from viruses to humans.