How does gene expression differ in prokaryotes and eukaryotes

When more protein is required, more transcription occurs. Therefore, in prokaryotic cells, the control of gene expression is almost entirely at the transcriptional level. Eukaryotic cells, in contrast, have intracellular organelles and are much more complex. The newly synthesized mRNA is transported out of the nucleus into the cytoplasm, where ribosomes translate the mRNA to produce protein.

The processes of transcription and translation are physically separated by the nuclear membrane; transcription occurs only within the nucleus, and translation only occurs outside the nucleus in the cytoplasm. The regulation of gene expression can occur at any stage of the process Figure 1 :.

The process occurs in both prokaryotic and eukaryotic cells, just in slightly different manners. Prokaryotic organisms are single-celled organisms that lack a cell nucleus, and their DNA therefore floats freely in the cell cytoplasm.

To synthesize a protein, the processes of transcription and translation occur almost simultaneously. When the resulting protein is no longer needed, transcription stops. As a result, the primary method to control what type of protein and how much of each protein is expressed in a prokaryotic cell is the regulation of DNA transcription. All of the subsequent steps occur automatically. When more protein is required, more transcription occurs. Therefore, in prokaryotic cells, the control of gene expression is mostly at the transcriptional level.

Eukaryotic cells, in contrast, have intracellular organelles that add to their complexity. The newly synthesized RNA is then transported out of the nucleus into the cytoplasm, where ribosomes translate the RNA into protein. The processes of transcription and translation are physically separated by the nuclear membrane; transcription occurs only within the nucleus, and translation occurs only outside the nucleus in the cytoplasm.

Gene Expression in Prokaryotes vs Eukaryotes. Gene expression is an essential process that takes place in both prokaryotes and eukaryotes. Despite the fact that the results in both eukaryotes and prokaryotes are the same, there are considerable differences between them. Gene expression is discussed in general, and the differences between the prokaryotic and eukaryotic processes are highlighted in particular in this article.

When the information of a gene is being converted into structural forms, the particular gene is said to be expressed. Gene expression is a process that makes biologically important molecules, and these are usually macromolecules.

Prokaryotes contain three promoter elements: one is upstream to the gene, second is 10 nucleotides downstream to it, and the third is 35 nucleotides downstream to it while eukaryotes contain a much larger set of promoter elements including the TATA box.

Thus, this is another difference between prokaryotic and eukaryotic gene expression. Furthermore, the transcription initiation factors of prokaryotes do not assemble with the initiation complex while the transcription initiation factors of eukaryotes assemble with the initiation complex. Introns do not interrupt the open reading frame of the prokaryotic genes while introns interrupt the open reading frame of the eukaryotic genes.

One other difference between prokaryotic and eukaryotic gene expression is that the prokaryotic gene expression is equipped with a single type of RNA polymerase while three RNA polymerases are employed in the eukaryotic gene expression.

Moreover, several functionally-related genes occur in clusters called operons in prokaryotes while eukaryotic genes occur individually. Also, prokaryotic gene expression results in polycistronic mRNA while eukaryotic gene expression results in monocistronic mRNA. This is another difference between prokaryotic and eukaryotic gene expression. Another difference between prokaryotic and eukaryotic gene expression is that prokaryotic gene expression does not include post-transcriptional modifications while eukaryotic gene expression includes post-transcriptional modifications.

One more difference between prokaryotic and eukaryotic gene expression is that the prokaryotes contain 70S ribosomes while eukaryotes contain 80S ribosomes. Besides, the regulation of the prokaryotic gene expression occurs at the transcriptional level while the regulation of the eukaryotic gene expression can occur at epigenetic level, transcriptional level, post-transcriptional level, translational level, and post-translational level.

Prokaryotic gene expression completely occurs in the cytoplasm and is controlled at transcriptional level.