Question

question 3 of 10
which sentence describes a way gene expression in eukaryotes is regulated after transcription but before translation begins?
a. coding regions of mrna can be clipped and reassembled in multiple possible combinations.
b. each gene has its own promoter that is recognized by specific transcription factors.
c. changes to histones uncoil chromatin in different areas to expose different genes.
d. chemical changes can prevent or alter polypeptide combinations.
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Explanation:

• Option A: mRNA splicing (clipping and reassembling coding regions) occurs after transcription (mRNA is made) and before translation (protein synthesis). This is a post - transcriptional (but pre - translational) regulation mechanism.
• Option B: Promoter recognition by transcription factors occurs during transcription initiation (before mRNA is fully formed), so it is a transcriptional regulation, not post - transcriptional.
• Option C: Changes to histones (uncoiling chromatin) affect the accessibility of DNA for transcription. This is a transcriptional regulation mechanism as it influences whether a gene is transcribed or not.
• Option D: Chemical changes that prevent or alter polypeptide combinations occur during or after translation (since polypeptides are the products of translation).

Answer:

A. Coding regions of mRNA can be clipped and reassembled in multiple possible combinations.