試題詳解

18. Lipid-soluble signaling molecules, such as aldosterone, cross the membranes of all cells but affect only target cells because
(A) Only target cells retain the appropriate DNA segments
(B) Intracellular receptors are present only in target cells
(C) Only target cells have enzymes that break down aldosterone
(D) Only in target cells is aldosterone able to initiate thephosphorylation cascade that turns genes on