Animation - Action of Glucocorticoid Hormone

re genes turned on or off permanently in each cell?

Gene expression varies between cells. A muscle cell will express different genes than a white blood cell even though both cells have identical genomes. Gene expression varies over time as well. Signals from other parts of the body can temporarily turn on or off specific genes in response to environmental conditions. By modifying gene expression organisms can respond to changes inside and outside of the body. While some genes may be turned on or off permanently at the time that the basic phenotype of the cell is determined, other genes are dynamic and change expression continuously in response to the local environment.

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