Question

Use the following model of a eukaryotic transcript to answer the question.

5' UTR E1 I1 E2 I2 E3 I3 E4 UTR 3'
Which of the following is a useful feature of introns for this model?
A. Introns protect exon structure.
B. Each intron has enzymatic properties.
C. Introns allow exon shuffling.
D. They are translated into small polypeptides.
E. They become parts of snRNPs.

Answer 1

Introns in a eukaryotic transcript enable exon shuffling, crucial for the diversity of protein production through alternative splicing(option c). They also play a role in gene regulation and mRNA transport.

Step-by-step explanation:

Considering the model of a eukaryotic transcript, which consists of a 5' untranslated region (UTR), exons (E1, E2, E3, E4) and introns (I1, I2, I3), and a 3' UTR, one useful feature of introns is C. Introns allow exon shuffling.

Introns are non-coding sequences that are spliced out of the pre-mRNA during the processing to form mature mRNA. This feature is essential as it allows cells to mix and match exons, which can increase the diversity of proteins that can be produced from a single gene through a process known as alternative splicing. Alternative splicing enables different mRNA transcripts that may exclude certain exons or include others, giving rise to various proteins with potentially different functions or properties.

In addition, introns play roles in gene regulation and mRNA transport, ensuring that the final transcript is accurately processed and capable of producing a functional protein. It is critical that intron sequences are precisely removed to prevent disrupting the exon sequence, which would result in nonfunctional proteins. Thus, in the provided model, 'introns allow exon shuffling' would be a beneficial aspect of the presence of introns within the eukaryotic transcript.