Which of the following structures is not directly involved in translation?

Transfer RNA (tRNA) is directly involved in translation as it serves as the adaptor molecule that brings specific amino acids to the ribosome, corresponding to the codons in the mRNA sequence. Each tRNA molecule is charged with a particular amino acid and matches its anticodon to the codon on mRNA, facilitating the assembly of proteins.

Messenger RNA (mRNA) is crucial for translation as it carries the genetic information transcribed from DNA to the ribosome, where proteins are synthesized. The sequence of nucleotides in mRNA determines the order of amino acids in the resulting protein, making it a direct participant in the translation process.

Ribosomes are the cellular structures where translation occurs, acting as the site for protein synthesis. They facilitate the binding of mRNA and tRNA and catalyze the formation of peptide bonds between amino acids, playing a central role in translating the genetic code into functional proteins.