Final answer:
The first event in protein synthesis is the binding of mRNA to the small ribosomal subunit, followed by the binding of initiator tRNA to the start codon, and then the large ribosomal subunit joins the complex.
Step-by-step explanation:
In protein synthesis, the correct sequence of events starts with the mRNA binding to the small ribosomal subunit. This complex then scans the mRNA for the start codon. Once the start codon is identified, which is typically AUG, the initiator tRNA, charged with the amino acid methionine, binds to this codon by complementary base pairing. Following this event, the large ribosomal subunit binds to form the complete initiation complex, which is now ready to facilitate the elongation phase of protein synthesis where peptide bonds will form between amino acids.