Final answer:
Hormones induce cellular responses by binding to specific receptors, which can be located intracellularly or on the cell surface, leading to direct gene regulation or activation of signaling pathways.
Step-by-step explanation:
The mechanism of hormone action is a key concept in biology that refers to how hormones bind to their respective receptors and elicit cellular responses. Hormones can exert their effects through intracellular receptors or cell surface receptors. When a hormone binds to an intracellular receptor, it often forms a receptor-hormone complex that can directly regulate gene expression within the nucleus. This process can enhance the synthesis of mRNA and promote enzyme synthesis, effectively increasing the speed of cellular reactions. Alternatively, when a hormone binds to a cell surface receptor, it activates a signaling pathway within the cell that can lead to various cellular changes.
Different hormones may function via distinct mechanisms depending on their chemical structure. For example, steroid hormones tend to be lipid-soluble and easily pass through the cell membrane to bind to intracellular receptors. Non-steroid hormones, which are not lipid-soluble, usually bind to receptors on the cell surface and often use a second messenger system to mediate changes within the target cell. The ultimate response of a cell to a hormone signal involves the regulation of numerous cellular processes, including gene expression, metabolic activities, and altered cell behavior.