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How does gene expression control the specialization of embryonic cells?
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human development
Growth of the human fetus from the fourth month to the ninth month of pregnancy.
In embryonic development, the specialization of cellsāa process known as cell differentiationāis driven by the differential expression of genes rather than the loss of genetic information. While all cells in an organism typically contain the same set of genes, they become specialized by expressing specific genes while repressing others.1
This regulation is achieved through several key mechanisms:
- Transcriptional Control: The most influential level of control involves transcription factors, which bind to regulatory DNA sequences to activate or inhibit the copying of genes into RNA.1
- Epigenetic Modifications: Chemical changes to DNA and histones, such as methylation and acetylation, alter chromatin structure. These modifications determine whether a gene is accessible for expression or silenced, effectively locking in a cell's specialized state.21
- Developmental Signaling: Early in development, cells receive instructions through cytoplasmic determinants inherited during division or through induction, where neighboring cells secrete signals that alter a cell's developmental path.3
- Lateral Inhibition: Cells can also use surface molecules, such as Notch and Delta, to communicate with neighbors, ensuring that adjacent cells adopt different fates by amplifying small initial differences in gene activity.3