Final answer:
During the initiation of translation, the large ribosomal subunit is the last component to join the initiation complex. This completes the formation of the complex and positions the initiator tRNA, allowing the translation process to proceed to the elongation stage.
Step-by-step explanation:
Initiation of Translation in Biology
The process of translation initiation in both prokaryotic and eukaryotic cells involves the formation of an initiation complex that ultimately leads to the synthesis of proteins. First, the mRNA binds to the small ribosomal subunit, often with the assistance of initiation factors. In eukaryotic cells, this involves the recognition of the 5' cap of the mRNA, whereas in prokaryotes, a sequence known as the Shine-Dalgarno sequence aids in this binding. Then, the initiator tRNA — carrying N-formyl-methionine in prokaryotes or methionine in eukaryotes — binds to the start codon of the mRNA by forming hydrogen bonds.
This is facilitated by the mRNA's codon and the tRNA's anticodon pairing up. The last component to join this assembly is the large ribosomal subunit. The binding of the large ribosomal subunit to the complex completes the initiation phase, positioning the initiator tRNA in the P site of the ribosome and preparing the complex for the elongation stage of protein synthesis. Therefore, the last component to join the initiation complex during the initiation of translation is the large ribosomal subunit (C).