What is the primary function of aminoacyl-tRNA synthetases?

Aminoacyl-tRNA synthetases play a crucial role in protein synthesis by catalyzing the attachment of specific amino acids to their corresponding transfer RNA (tRNA) molecules. This process is essential for the accuracy of translation, as the correctly charged tRNA carries the appropriate amino acid to the ribosome during protein synthesis.

Each aminoacyl-tRNA synthetase is specific to one amino acid and its corresponding tRNAs, ensuring that the correct amino acid is incorporated into the growing polypeptide chain. This specificity is vital for maintaining the fidelity of protein translation, as errors in amino acid incorporation can lead to malfunctioning proteins.

The other options relate to different aspects of protein synthesis or tRNA function but do not accurately describe the primary role of aminoacyl-tRNA synthetases. For instance, modifications to tRNA molecules are typically performed by other enzymes, while proper protein folding and translation initiation are managed by different cellular mechanisms. Therefore, the answer highlighting the function of bonding amino acids to tRNAs is indeed the most accurate.