[Campbell Biology P.401] Which of the following statements accurately describes a step or co... | Practice Question

Which of the following statements accurately describes a step or component involved in the initiation of translation, as illustrated and described in the provided text and Figure 17.19?

  • A: In bacteria, the mRNA binding site on the small ribosomal subunit recognizes a specific nucleotide sequence *downstream* of the start codon.
  • B: The initiator tRNA carries the amino acid methionine and its anticodon (UAC) base-pairs with the AUG start codon.
  • C: The formation of the translation initiation complex is completed by the attachment of the large ribosomal subunit *before* the small ribosomal subunit binds to mRNA.
  • D: Hydrolysis of ATP provides the energy for the assembly of the translation initiation complex.

Explanation

The initiation of translation involves several key steps. The initiator tRNA carries methionine and its anticodon UAC base-pairs with the AUG start codon on the mRNA. In bacterial cells, the small ribosomal subunit binds to a specific sequence upstream of the start codon on the mRNA. The formation of the complete initiation complex requires the sequential attachment of the small and then the large ribosomal subunits, and this process is fueled by the hydrolysis of GTP, not ATP.