Final answer:
Exposure to extracellular signals via nuclear signaling pathways can result in protein synthesis, changes in metabolism, cell growth, or apoptosis. Nuclear signaling generally has a slower response due to the requirement of gene transcription and translation. Proper regulation of these signaling pathways is essential to avoid overactivation and maintain cellular homeostasis.
Step-by-step explanation:
The response produced by exposure to extracellular signals in a nuclear signaling pathway can include a variety of cellular actions such as protein synthesis, changes in metabolism, cell growth, or programmed cell death (apoptosis). These pathways often initiate gene expression through multiple mechanisms such as activating enzymes that interact with DNA transcription factors, modifying proteins and altering their location in the cell, or storing and mobilizing energy resources. Nuclear signaling pathways typically have a slower response time compared to other signaling mechanisms because they involve transcription and translation of genes, which are intrinsically more time-consuming processes.
Signaling cascades also play a role in cells’ responses to immediate needs, such as the need for glucose in muscle cells. Additionally, cell growth is frequently stimulated by extracellular growth factors, while uncontrolled growth can lead to cancer. The pathway is carefully regulated, including a proper termination step to avoid overactivation, which is often achieved through the degradation of signaling molecules and dephosphorylation of intermediates by phosphatases.