How does a nonsteroid hormone effect change in a target cell?

• A. By binding to a receptor on the cell membrane and activating a second messenger system.
• B. By entering the cell and directly altering DNA transcription.
• C. By directly interacting with the cell's mitochondria to alter energy production.
• D. By diffusing through the cell membrane and binding to intracellular receptors.

Answer: (A)

Verified step by step guidance

1. Understand the nature of nonsteroid hormones: Nonsteroid hormones are typically water-soluble and cannot pass through the lipid bilayer of cell membranes.
2. Identify the mechanism of action: Nonsteroid hormones bind to specific receptors located on the surface of the target cell's membrane.
3. Explore the role of second messengers: Once the hormone binds to the receptor, it activates a second messenger system inside the cell. Common second messengers include cyclic AMP (cAMP), calcium ions, and inositol triphosphate (IP3).
4. Examine the effects of second messengers: The second messengers amplify the signal and initiate a cascade of biochemical reactions within the cell, leading to changes in cellular activity.
5. Consider the implications: This mechanism allows nonsteroid hormones to exert their effects without entering the cell, contrasting with steroid hormones that typically enter the cell and directly influence gene transcription.