#Question id: 4296

 Normally, a stop codon is required to release the ribosome from an mRNA but what happens to a ribosome that initiates translation of an mRNA fragment that lacks a termination codon. The Ribosome stalled at broken part of mRNA. In prokaryotic cells, such stalled ribosomes are rescued by the action of a chimeric RNA molecule that is part tRNA and part mRNA, appropriately called a tmRNA. What is sequence of events of this rescue process.

A. Translocation of the peptidyl-SsrA RNA results in the release of the broken mRNA

B. the SsrAAla–EF-Tu–GTP complex binds to the A-site of the ribosome and participates in the peptidyl transferase reaction

C. portion of the SsrA RNA acts as an mRNA and encodes 10 codons followed by a stop codon

D. the protein encoded by the incomplete mRNA is fused to a 10-amino-acid “peptide tag” at its carboxyl terminus, and the ribosome is recycled. Interestingly, the 10-amino-acid tag is recognized by cellular proteases that rapidly degrade the tag and the truncated polypeptide to which it is attached