A point mutation in a eukaryotic gene disrupts the conserved 5' splice donor (GU) of intron 1. The pre-mRNA is otherwise normal.
A point mutation that disrupts the GU at the 5' splice site of intron 1 most likely results in:
- A
No effect, because spliceosomes ignore single base changes.
- B
Excision of an extra exon.
- C
Increased translation efficiency due to longer mRNA.
- Dcheck_circle
Retention of intron 1 in the mature mRNA, often leading to a frameshift or premature stop.
Explanation
The 5' splice donor (typically GU) and 3' acceptor (AG) are recognized by the spliceosome. Disrupting the donor blocks correct splicing, retaining the intron and frequently introducing premature stop codons.