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MBBS QUESTION #10373
Question 1
Steroid hormones (e.g., cortisol, estrogen, testosterone), being lipid-soluble, characteristically exert their effects on target cells via which mechanism?
  • Binding exclusively to cell-surface G-protein coupled receptors
  • Diffusing directly across the plasma membrane to bind intracellular or nuclear receptors, which then function as ligand-activated transcription factors altering gene expression✔️
  • Binding ligand-gated ion channels at the cell surface
  • Requiring an obligatory second-messenger system, with no direct genomic (transcriptional) action possible
Correct Answer Explanation
Being small and lipophilic, steroid hormones cross the plasma membrane directly and bind intracellular or nuclear receptors; the hormone-receptor complex then acts as a transcription factor, binding hormone response elements in DNA to alter gene expression — a mechanism producing slower-onset but often longer-lasting effects compared with peptide hormone signaling.