The first step in eukaryotic pre-mRNA splicing is
A) ligation of the two exon sequences.
B) cleavage of the intron sequence at the branch site.
C) ligation of the branch site adenosine to the 5' end of the intron.
D) cleavage of the intron sequence at the 3' end.
E) ligation of U1 snRNA to the branch site.

Question

Quizplus · Accepted Answer

The first step in eukaryotic pre-mRNA splicing involves the formation of a lariat structure, where the branch site adenosine attacks the 5' splice site, creating a loop.

The First Step in Eukaryotic Pre-MRNA Splicing Is