Transcription & Translation MCAT Practice Question
A molecular biologist investigates ribosomal frameshifting during translation of a viral gene. The viral mRNA contains a slippery sequence (GGGUUUU) followed immediately by an RNA secondary structure (pseudoknot). When the ribosome encounters this region, it occasionally shifts reading frame by -1 nucleotide. What is the likely mechanism and consequence?
Answer choices
- AThe pseudoknot causes ribosomal stalling, allowing tRNA to slip backward and shift the reading frame, producing an alternate proteinCorrect answer
- BThe slippery sequence is recognized by release factors, prematurely terminating translation
- CThe pseudoknot is a binding site for initiation factors that reposition the ribosome
- DThe secondary structure prevents the ribosome from elongating, causing mRNA degradation
- EThe frameshift allows readthrough of a normal stop codon into downstream sequence
- FThe slippery sequence causes dissociation of ribosomal subunits, requiring reinitiation at a downstream AUG codon
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