If splice site consensus sequences mutate, what is the likely outcome?

If splice site consensus sequences mutate, what is the likely outcome?

• A. Mutations at 5' GU or 3' AG disrupt splicing and intron removal
• B. Mutations have no effect on splicing
• C. They only affect translation, not splicing
• D. They enhance transcription rate

Answer: (A)

Splice site signals are the markers the cellular machinery uses to know where introns begin and end. The 5' end of an intron (donor site) normally has GU, and the 3' end (acceptor site) has AG. When these sequences mutate, the spliceosome can’t recognize the boundaries correctly, so introns aren’t removed properly. The result is aberrant mRNA—through intron retention, exon skipping, or activation of cryptic splice sites—which often produces a faulty protein. So the most likely outcome is disrupted splicing and failure to remove introns accurately; changes to transcription rate or translation alone aren’t the primary consequence of these mutations.

Splice site signals are the markers the cellular machinery uses to know where introns begin and end. The 5' end of an intron (donor site) normally has GU, and the 3' end (acceptor site) has AG. When these sequences mutate, the spliceosome can’t recognize the boundaries correctly, so introns aren’t removed properly. The result is aberrant mRNA—through intron retention, exon skipping, or activation of cryptic splice sites—which often produces a faulty protein. So the most likely outcome is disrupted splicing and failure to remove introns accurately; changes to transcription rate or translation alone aren’t the primary consequence of these mutations.