1. Anticodon Loop: Each tRNA molecule has a specific three-nucleotide sequence called the anticodon located in a loop structure. This anticodon is complementary to a specific three-nucleotide codon on the mRNA molecule.
2. Codon-Anticodon Pairing: During translation, the tRNA anticodon base pairs with the mRNA codon. This pairing follows the rules of complementary base pairing (A with U, and C with G).
3. Amino Acid Attachment: Each tRNA molecule is covalently linked to a specific amino acid. The amino acid that is attached to a tRNA is determined by the aminoacyl-tRNA synthetase enzyme. This enzyme recognizes both the specific tRNA and its corresponding amino acid, ensuring that the correct amino acid is attached.
Therefore, the tRNA "knows" what amino acid is coded on the mRNA because its anticodon precisely matches the codon on the mRNA, and it carries the corresponding amino acid. This accurate matching process ensures that the correct amino acids are incorporated into the growing polypeptide chain during protein synthesis.
