Use the following model of a eukaryotic transcript to answer the question. E1-4 refer to the exons and I1-3 refer to the introns in the pre-mRNA transcript.
5' UTR E1 I1 E2 I2 E3 I3 E4 UTR 3'
Suppose that exposure to a chemical mutagen results in a change in the sequence that alters the 5' end of intron 1 (I1). Which of the following results might occur?

Question

Quizplus · Accepted Answer

A mutation in the 5' end of intron 1 could affect splicing of the pre-mRNA, leading to the inclusion of intron 1 in the final mRNA sequence. This may result in a truncated or altered protein product, but the gene product would still be present. It is less likely to result in loss of the entire gene product or loss of just E1. Premature stop codons could occur if the mutation disrupted an exon, but this is not likely given the location of the mutation specified in the question.

Use the Following Model of a Eukaryotic Transcript to Answer