Synonymous Codons are not the Same with Respect to the Speed of Translation Elongation

In the genetic code table, out of the 64 triplet codons, generally 61 codons are involved in coding for the 20 amino acids in organisms. Therefore, the genetic code table is an obvious degenerate: except Met and Trp, each of the 18 amino acids is coded by 2-6 synonymous codons. Synonymous codons (Box 1) not only encode the same amino acid, but are similar to each other with regard to their nucleotide sequences as well as distribution in the table. Therefore, study of these codons in different genomes has been of great interest to molecular evolutionary biologists.