Final answer:
The specificity between an amino acid and its tRNA is determined by the unique tRNA molecule. Each tRNA has a specific shape and carries a specific anticodon that interacts with the corresponding codon on the mRNA. This interaction ensures that the correct amino acid is inserted into the growing polypeptide chain during protein synthesis.
Step-by-step explanation:
The specificity between an amino acid and its tRNA is determined by each individual tRNA. Each tRNA is specific for one of the 20 amino acids. The particular shape of the tRNA dictates this specificity. Each tRNA has a separate anticodon, a sequence of three nucleotides complementary to the corresponding codon on the mRNA. This codon-anticodon interaction ensures that the correct amino acid is inserted into the growing polypeptide chain during protein synthesis.