How do nonsteroid hormones differ from steroid hormones in their mechanism of action?

• A. Nonsteroid hormones are synthesized from cholesterol, while steroid hormones are derived from amino acids.
• B. Nonsteroid hormones bind to receptors on the cell surface, while steroid hormones enter the cell and bind to intracellular receptors.
• C. Nonsteroid hormones directly activate genes, while steroid hormones use second messengers.
• D. Nonsteroid hormones are lipid-soluble and can pass through the cell membrane, while steroid hormones are water-soluble and cannot.

Answer: (B)

Verified step by step guidance

1. Identify the chemical nature of nonsteroid and steroid hormones: Nonsteroid hormones are typically derived from amino acids, while steroid hormones are synthesized from cholesterol.
2. Understand the solubility properties: Nonsteroid hormones are generally water-soluble, meaning they cannot easily pass through the lipid bilayer of the cell membrane. In contrast, steroid hormones are lipid-soluble, allowing them to pass through the cell membrane.
3. Examine the mechanism of action for nonsteroid hormones: Since they are water-soluble, nonsteroid hormones bind to specific receptors on the surface of the target cell. This binding triggers a cascade of intracellular events often involving second messengers, such as cyclic AMP (cAMP), to relay the signal inside the cell.
4. Explore the mechanism of action for steroid hormones: Being lipid-soluble, steroid hormones can diffuse through the cell membrane and bind to intracellular receptors, typically located in the cytoplasm or nucleus. This hormone-receptor complex then directly interacts with the cell's DNA to regulate gene expression.
5. Compare the outcomes of hormone-receptor interactions: Nonsteroid hormones primarily use second messengers to exert their effects, leading to a rapid but often short-lived response. Steroid hormones, by directly influencing gene expression, tend to have longer-lasting effects on the target cell's function.