Question

which mrna sequence does not play a role in intron splicing?
the 3 splice site
an adenine nucleotide 18–40 nucleotides upstream of the 3 splice site
the branch point
the 5 splice site
the shine–dalgarno sequence

Explanation:

The 5' splice site, 3' splice site, branch point (an adenine 18-40 nucleotides upstream of the 3' splice site) are all critical sequences for eukaryotic pre-mRNA intron splicing. The Shine-Dalgarno sequence is a prokaryotic mRNA sequence that helps recruit the ribosome for translation, with no role in intron splicing.

Answer:

the Shine-Dalgarno sequence