Question

Which of these methods of controlling eukaryotic gene expression is NOT employed in prokaryotic cells?

A. controlling how often a gene is transcribed
B. controlling how an RNA transcript is spliced
C. controlling which mRNAs are exported from the nucleus to the cytosol
D. controlling which mRNAs are translated into protein by the ribosomes
E. controlling how rapidly proteins are destroyed once they are made

Answer 1

The control of mRNA export from the nucleus to the cytosol is a method of gene expression regulation not employed by prokaryotic cells, as they lack a nucleus. This process is specific to eukaryotic cells, which compartmentalize transcription and translation between the nucleus and cytoplasm.

Step-by-step explanation:

The method of controlling eukaryotic gene expression that is NOT employed in prokaryotic cells is C. controlling which mRNAs are exported from the nucleus to the cytosol. Prokaryotic organisms, being single-celled and without a nucleus, do not go through the process of exporting mRNA from the nucleus as all their transcription and translation activities occur in the cytoplasm. Contrastingly, eukaryotic cells, which have both cytoplasm and a nucleus, must transport the transcribed mRNA from the nucleus to the cytoplasm where it can be translated by ribosomes into proteins.

While prokaryotic cells control gene expression primarily at the transcriptional level, eukaryotic cells regulate gene expression at multiple levels including epigenetic, transcriptional, post-transcriptional, translational, and post-translational stages. The compartmentalization in eukaryotes allows for additional regulatory mechanisms such as mRNA splicing and transport, which are not present in prokaryotes due to the lack of a nucleus.