What are the major differences between prokaryotic and eukaryotic gene expression?

Question

Prokaryotic gene expression occurs in the cytoplasm because prokaryotic cells lack a nucleus. Transcription and translation occur simultaneously. In eukaryotes, gene expression is more complex. Transcription happens in the nucleus, producing mRNA, which is then processed (capping, splicing, polyadenylation) before being exported to the cytoplasm for translation. Additionally, eukaryotic cells have multiple types of RNA polymerase, whereas prokaryotes have a single RNA polymerase. Regulatory mechanisms such as enhancers, silencers, and transcription factors further complicate gene expression in eukaryotes.

Answer 1

Appreciable question!! The major differences between prokaryotic and eukaryotic gene expression center around the complexity, location, and regulation of the process. Here’s a clear break down of these distinguished cells

1. Location of Gene Expression

Prokaryotes:

• Transcription and translation occur simultaneously in the cytoplasm.

Eukaryotes:

• Transcription happens in the nucleus, and translation occurs in the cytoplasm after mRNA is processed and exported.

2. mRNA Processing

Prokaryotes:

• mRNA is not processed (no splicing, no 5’ cap, no poly-A tail).

• The mRNA is often polycistronic (can encode multiple proteins from one mRNA).

Eukaryotes:

• mRNA undergoes extensive processing:

• 5’ capping

• 3’ poly-A tail addition

• Splicing (removal of introns)

• mRNA is usually monocistronic (one gene per mRNA).

3. Gene Regulation

Prokaryotes:

• Mainly regulated at the transcriptional level using repressors/activators and operons.

Eukaryotes:

• More complex regulation at multiple levels:

• Epigenetic (DNA methylation, histone modification)

• Transcriptional (enhancers/silencers)

• Post-transcriptional (splicing, mRNA stability)

• Translational and post-translational

4. Transcription Machinery

Prokaryotes:

• A single RNA polymerase transcribes all types of RNA.

Eukaryotes:

• Three different RNA polymerases (Pol I, II, III) for different RNA types.

5. Chromatin Structure

Prokaryotes:

• No chromatin; DNA is freely accessible.

Eukaryotes:

• DNA is wrapped around histones to form chromatin, which affects gene accessibility and expression.