Question

In prokaryotic cells, formation of the initiation complex requires the binding of tRNAfMet to the ______ site of the ribosome.

Answer 1

In the initiation complex of prokaryotic cells, the tRNA carrying N-formyl-methionine, known as tRNAfMet, binds to the P site of the ribosome. This step is crucial for the beginning of protein synthesis.

Step-by-step explanation:

In prokaryotic cells, the formation of the initiation complex for protein synthesis begins when the small ribosomal subunit binds with initiation factors (IFs) and an initiator tRNA at the start codon of mRNA. Specifically, this tRNA, known as tRNAfMet, carries the amino acid N-formyl-methionine. In this process, the initiator tRNA binds to the P (peptidyl) site of the ribosome.

The interaction is facilitated by the initiation factor IF-2, and once bound, the initiation complex is ready to join with the large ribosomal subunit to proceed with protein synthesis. fMet-tRNAfMet specifically begins every polypeptide chain in organisms like E. coli but is removed after protein synthesis is completed.