Final answer:
Non-steroid hormones bind to cell membrane receptors and initiate a signaling cascade that indirectly influences gene expression and protein synthesis.
Step-by-step explanation:
Non-steroid hormones react in cells by binding to cell membrane receptors. Unlike steroid hormones, which can diffuse directly through the cell membrane due to their lipid-solubility and bind to receptors inside the cell, non-steroid hormones are typically hydrophilic and cannot pass through the lipid bilayer of the cell membrane. Instead, they bind to cell surface receptors, initiating a signaling cascade through second messengers that indirectly influences cellular processes, such as the making of functional proteins. This indirect pathway may lead to changes in gene expression and protein synthesis, but it occurs outside of the nucleus and does not involve the direct entry of the hormone into the nucleus.