Final answer:
The binding of signaling molecules to cell-surface receptors initiates a signaling pathway, leading to various cellular responses such as metabolic changes, gene expression, and programmed cell death. The regulation of these pathways is crucial for cell health, and their dysfunction can lead to diseases like cancer.
Step-by-step explanation:
When signaling molecules bind to cell-surface receptors, this initiates a signaling pathway or cascade. This pathway can lead to a wide range of cellular responses, such as changes in metabolism, gene expression, or even programmed cell death (apoptosis). Second messengers and enzymes within this cascade interact with each other to propagate the signal inside the cell, which ultimately causes a change in the cell's environment or activities.
Some of the possible responses to a signaling pathway include storage of energy as glycogen or fat, use of glucose for energy, stimulation of cell growth through growth factors, or the initiation of apoptosis to safely dismantle a cell without releasing harmful substances.
Specific examples of cellular responses include the upregulation of proteins related to metabolism in response to energy needs or the initiation of apoptosis when cells are deprived of signals from the extracellular matrix. Regulation of these pathways is crucial for maintaining cell health and function; an unregulated signaling pathway can lead to cancer or other diseases. Degradation of signaling molecules and dephosphorylation of intermediates are common ways to terminate signaling pathways and ensure appropriate responses.