Question

A scientist introduces a mutation that makes the 60S ribosomal subunit nonfunctional in a human cell line. What would be the predicted effect on translation?

Translation stalls after the initiation AUG codon is identified.
The ribosome cannot catalyze the formation of peptide bonds between the tRNAs in the A and P sites.
The ribosome cannot interact with mRNAs.
tRNAs cannot exit the E site of the ribosome.

Answer 1

Answer: Translation stalls after the initiation AUG codon is identified.

Step-by-step explanation:

The 60S subunit is the large subunit of eukaryotic 80S ribosomes. It contains many additional protein segments, as well as ribosomal RNA expansion segments.

AUG is a start codon, the first codon of a messenger RNA transcript translated by a ribosome. After it, the translation proceeds until the codon stop.

Once the small ribosomal subunit with its bound Met-tRNAiMet (the tRNA complementary with the start codon) is correctly positioned at the start codon, the union with the large 60S ribosomal subunit completes formation of the 80S initiation complex. Without this 60S subunit, the complex can not be formed thereby the translation can not proceed.