[Campbell Biology P.1053] A student proposes injecting a water-soluble hormone directly into ... | Practice Question

A student proposes injecting a water-soluble hormone directly into the cytosol of a target cell to achieve a faster response. Based on your understanding of hormone mechanisms, what would be the most likely outcome?

  • A: The hormone would bind to intracellular receptors and trigger a normal response.
  • B: The hormone would be immediately degraded by cytoplasmic enzymes, preventing any response.
  • C: No significant physiological response would occur because water-soluble hormones primarily bind to receptors on the cell surface.
  • D: The cell's metabolism would dramatically increase due to direct access to the cell's machinery.

Explanation

Water-soluble hormones are hydrophilic and cannot easily cross the lipid bilayer of the cell membrane. Their receptors are located on the cell surface. Signal transduction pathways are initiated when the hormone binds to these surface receptors. Injecting the hormone directly into the cytosol bypasses the location of its primary receptors, thus preventing the normal signaling cascade and physiological response.