Why gene regulation is essential for viruses, prokaryotes and eukaryotes?

Regulation of gene expression is critical in many facets of cell biology:

1. Fine regulation of gene expression allows for the precise response to:

• Stress events
  
• Cell-cell signalling
  
• Inner-cell signalling
  

2. Cell differentiation: Different gene expression allows for cells to differentiate in different cell types although they possess the same DNA

3. Studying the gene regulation is critical to understand cancer and disease since most of the time it depends on the misregulation of genes involved in tumour suppression or tumour progression.