Final answer:
Lipid-soluble hormones can enter a cell, bind to intracellular receptors, and regulate gene expression by acting as transcription regulators.
Step-by-step explanation:
Once inside the cell, lipid-soluble hormones can bind to intracellular receptors and modulate gene expression. These hormones permeate the plasma membrane and either bind with receptors in the cytoplasm or directly interact with receptors within the nucleus. By forming a hormone-receptor complex, these hormones act as transcription regulators, controlling the synthesis of specific proteins by affecting the transcription of particular genes.
Lipid-soluble hormones, such as steroid hormones, vitamin D, and thyroxine, are able to diffuse across the cell membrane due to their lipophilic nature. Upon entering the target cell, they bind to intracellular receptors, a process that culminates in the regulation of gene expression. This contrasts with water-soluble hormones, which are unable to pass through the lipid bilayer and thus bind to receptors on the cell surface, initiating a cascade of second messenger systems.