Overview
This section explains why gene expression is regulated in cells, details the main differences between regulation in prokaryotes and eukaryotes, and introduces the multiple levels at which eukaryotic gene expression can be controlled.
Importance of Gene Regulation
- Cells regulate gene expression to produce proteins at the right time and place for proper function.
- Gene expression is the process of turning on a gene to make RNA and protein from DNA.
- Regulation ensures resources are used efficiently and prevents cells from making unnecessary proteins.
- Failure in gene regulation can cause diseases such as cancer.
Gene Expression in Prokaryotes
- Prokaryotes lack a nucleus; their DNA is free in the cytoplasm.
- Transcription and translation happen simultaneously in prokaryotes.
- Most gene regulation in prokaryotes occurs at the transcriptional level.
- When proteins are not needed, transcription stops, saving energy and resources.
Gene Expression in Eukaryotes
- Eukaryotes contain a nucleus; DNA is confined within it.
- Transcription occurs in the nucleus; translation takes place in the cytoplasm.
- Gene regulation can happen at multiple steps: epigenetic, transcriptional, post-transcriptional, translational, and post-translational.
- Eukaryotic gene regulation is more complex due to compartmentalization and organelles.
Evolution of Gene Regulation
- Prokaryotic gene regulation focuses on controlling transcription.
- Eukaryotic evolution led to more complex control, including compartmentalization and gene silencing for defense.
- Evolution of regulatory complexity helped organisms adapt and survive environmental challenges.
Key Terms & Definitions
- Gene expression — Turning on a gene to produce RNA and protein.
- Transcription — The process of copying DNA into RNA.
- Translation — The process of making protein from RNA.
- Transcriptional regulation — Control of gene expression at the RNA synthesis stage.
- Epigenetic regulation — Control by DNA packaging/unpacking and chromatin structure.
- Post-transcriptional regulation — Control after RNA is made, such as RNA processing and export.
- Translational regulation — Control of the protein-making process from mRNA.
- Post-translational regulation — Control after a protein is made, like modification or degradation.
Action Items / Next Steps
- Review Table 16.1 to compare prokaryotic and eukaryotic gene regulation.
- Read upcoming sections for details on each level of gene regulation.