Which cellular processes can regulate gene expression in eukaryotes?

• A. Passage of mRNA through the nuclear membrane
• B. Destruction of the mRNA
• C. Rate of protein synthesis
• D. All of the above

Answer: (D)

Regulation of gene expression in eukaryotes happens at multiple post-transcriptional steps. After transcription, mRNA must be exported from the nucleus to the cytoplasm; controlling this passage determines which transcripts are available for translation. The stability of mRNA also shapes expression levels: transcripts that are degraded quickly produce less protein, while more stable mRNA persists longer and yields more protein. Finally, the rate of protein synthesis reflects how efficiently each mRNA is translated, with initiation and other factors tuning how much protein is made from the transcript. Because each of these steps can modulate protein output, the option that encompasses all of them best describes how gene expression can be regulated in eukaryotes.