Final answer:
The anticodon of tRNA pairs with the complementary codon on mRNA by the base-pairing rules, where A pairs with U and G pairs with C. tRNA molecules can also wobble at the third position to pair with multiple codons for the same amino acid. The tRNA structure and its recognition by specific enzymes ensure the correct amino acid is added to the polypeptide chain.
Step-by-step explanation:
The base-pairing rules between the anticodon of tRNA and the codon on mRNA are specific and follow the traditional DNA base-pairing rules where adenine (A) pairs with uracil (U) and guanine (G) pairs with cytosine (C), with thymine (T) in DNA being replaced by uracil in RNA.
During the process of translation, each tRNA molecule has a specific three-nucleotide anticodon sequence that is complementary to a specific codon on the mRNA. This ensures that the correct amino acid is added to the growing polypeptide chain. Additionally, some tRNA molecules can wobble at the third position, allowing them to bind to multiple codons that encode for the same amino acid.
The uniqueness of tRNA and its ability to correctly pair with mRNA codons is also determined by its 3D structure and chemical properties, which are recognized by specific enzymes called aminoacyl-tRNA synthetases. These enzymes charge the tRNA with the correct amino acid before it goes to the ribosome for protein synthesis.
For example, the mRNA codon GCA is recognized by a tRNA with the anticodon UGC, which carries the amino acid alanine. This is because the bases in UGC are complementary to those in GCA, allowing the bases to form stable pairs during translation.