In polypeptide synthesis, what moves to the ribosomes after DNA generates mRNA?

In polypeptide synthesis, following the transcription of DNA into mRNA, the next crucial step involves the translation of that mRNA into a polypeptide chain at the ribosomes. The molecule that plays a key role in this translation process is transfer RNA (tRNA).

tRNA is responsible for bringing the appropriate amino acids to the ribosome, where the mRNA sequence is read. Each tRNA molecule has an anticodon that pairs with a corresponding codon on the mRNA strand, ensuring that the correct amino acids are added in the correct order to form the growing polypeptide. This process is essential for synthesizing proteins based on the genetic information encoded in the mRNA.

The other options serve different roles in the cellular processes. Ribosomal RNA (rRNA) is a structural and functional component of ribosomes but does not directly transport amino acids. DNA remains in the nucleus and does not move to the ribosome for translation. Heterogeneous nuclear RNA (hnRNA) is a precursor to mRNA and is processed before it can be translated; it does not directly participate in the translation process either. Therefore, tRNA is the correct molecule that moves to the ribosomes after mRNA is generated from DNA.