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2.5 Steroid & Thyroid (Intracellular Receptor) Mechanism — Test 1
Q1. Steroid and thyroid hormones act on target cells by:✓ Crossing the membrane and binding intracellular receptors that act as transcription factors
Q2. Which hormone initiates its action by crossing the plasma membrane and binding an intracellular receptor?✓ Estradiol
Q3. The signal-transduction route for steroid hormones is best described as:✓ Diffuse through the membrane and bind intracellular receptors
Q4. The activated steroid hormone-receptor complex produces its effect by binding to:✓ Specific response elements on DNA
Q5. Thyroid hormone, although derived from an amino acid, acts on its targets by a:✓ Steroid-hormone (nuclear receptor) mechanism
Q6. Progesterone modulates gene expression by binding a receptor and acting at the:✓ Progesterone response element upstream of target genes
Q7. Testosterone, as a steroid hormone, binds receptors located:✓ Intracellularly (nuclear), forming a transcription-factor complex
Q8. Match each hormone with the protein it induces (a nuclear-receptor action) and choose the correct option.✓ A-iii, B-i, C-ii
Q9. Which of the following acts via an intracellular (nuclear) receptor?✓ Cortisol
Q10. Aldosterone increases renal Na+ reabsorption by inducing the synthesis of:✓ Na+ channels (and Na+/K+-ATPase) in principal cells
Q11. The patients with Graves disease and Cushing syndrome overproduce hormones that share which feature?✓ They act via intracellular receptors that bind DNA
Q12. Before binding hormone, the glucocorticoid receptor is typically located:✓ In the cytoplasm (complexed with HSP90), moving to the nucleus on binding
Q13. The overall response time of steroid/thyroid hormone action is:✓ Slow in onset and long in duration (gene transcription)
Q14. 1,25-Dihydroxycholecalciferol (vitamin D) acts like a steroid hormone because it:✓ Binds an intracellular receptor and induces genes (e.g. calbindin)
Q15. Which list contains ONLY hormones that use intracellular (nuclear) receptors?✓ Cortisol, estradiol, thyroid hormone, vitamin D
Q16. High cortisol can occupy mineralocorticoid receptors. This receptor cross-reactivity at high hormone levels is termed:✓ Specificity spillover
Q17. The result of a steroid hormone-receptor complex binding its DNA response element is:✓ Altered transcription producing new mRNA and protein
Q18. Because steroid and thyroid hormones are lipophilic, in the blood they are largely:✓ Carried bound to plasma transport proteins
Q19. Which hormone does NOT act through a cell-surface receptor?✓ Aldosterone
Q20. A defining structural feature shared by steroid and thyroid hormone receptors is the presence of:✓ A DNA-binding domain and a ligand-binding domain