Final answer:
Cells sense extracellular signals to control gene expression and cell fate. Signals can enter cells and bind to receptors, leading to the production of transcription factors that regulate gene expression. These factors bind to specific DNA sequences associated with the genes they control.
Step-by-step explanation:
Cells sense extracellular environmental signals, such as chemicals in the air, water, or body fluids, to control gene expression and cell fate. These signals can come from hormones released during developmental programs or in response to nutrient levels. The signals can enter cells and bind to intracellular receptors or bind to cell surface receptors to transduce molecular signals inside the cell. This signaling eventually leads to the production of transcription factors, which bind to specific regulatory DNA sequences associated with the genes they control. These sequences can be enhancers or silencers, turning on or suppressing gene transcription, respectively.