Splice-site mutations
A mutation changes the GU at the 5′ end of an intron. What is the most likely result?
Answer C: explanation for every choice
A
Intron sequences at the splice sites are what direct their own removal.
B
The promoter lies upstream of the gene, not inside an intron.
C
Correct. The spliceosome recognizes the GU at the 5′ splice site, so mutating it disrupts correct intron removal.
D
5′ capping happens at the start of the transcript, independent of splice sites.
TakeawayIntrons usually begin with GU and end with AG. Mutating these disrupts splicing.
See your set score →
Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID bb128.