Cellular differentiation is explained by differential gene expression rather than by differences in genetic content: every somatic cell of an organism carries the same DNA, and cell identity arises because distinct subsets of genes are transcribed ("turned on") or silenced ("turned off"), producing distinct complements of protein that determine a cell's morphology and function. Two classes of mechanism establish which genes are expressed — asymmetric segregation of cytoplasmic determinants, in which unevenly distributed transcription factors and their mRNA precursors are partitioned unequally among daughter cells at division, and inductive signaling, in which one group of cells causes another to differentiate via diffusible signals, direct cell-surface contact, or transfer through gap junctions. The concept belongs to cell and developmental biology, connects the central dogma to embryological pattern formation, and is bounded by the potency hierarchy: a pluripotent stem cell may adopt any somatic fate, while a terminally specialized cell neither differentiates further nor spontaneously de-differentiates.
Cellular differentiation is explained by differential gene expression rather than by differences in genetic content: every somatic cell of an organism carries the same DNA, and cell identity arises b…