Differential gene expression controls organismal development by regulating which genes are activated or repressed in different cells, despite all cells containing the same genome. This selective gene activation leads to cell differentiation, where cells become specialized in structure and function, forming the diverse tissues and organs of a multicellular organism. Key points include:
- Cell type diversity arises from differential gene expression : Different cells express different sets of genes, which produce distinct proteins that define each cell’s identity and function. This process is fundamental for development and differentiation from a single fertilized egg to a complex organism
- Gene expression is regulated by transcription factors and enhancers : Specific DNA sequences (enhancers) and proteins (transcription factors) control the transcription of target genes in a cell-type-specific manner, enabling precise spatial and temporal gene activation during development
- Morphogen gradients influence gene expression patterns : Concentration gradients of signaling molecules called morphogens determine gene expression in embryonic cells depending on their position, guiding cells to adopt different fates and organize into tissues and organs
- Epigenetic mechanisms and chromatin modifications stabilize gene expression patterns : Changes in chromatin structure, such as histone acetylation, regulate accessibility of genes to transcription machinery, locking in cell fate decisions and ensuring stable differentiation
- Only a subset of genes is expressed in each cell : While all cells retain the full genome, only genes relevant to a cell’s specialized function are expressed; unused genes remain intact but inactive, allowing potential plasticity in early development
In summary, differential gene expression orchestrates organismal development by controlling which genes are turned on or off in each cell, driving the specialization and organization of cells into functional tissues and organs throughout the life of the organism
