Steroid Hormones

Question

Steroid hormones
A) are proteins.
B) cannot diffuse through cell membranes.
C) bind to receptors in the nucleus of their target cells.
D) act on target cells by activating second messenger cascades.
E) are transported in the blood dissolved in the plasma.

Accepted Answer

Steroid hormones are lipid-soluble molecules that can easily diffuse through the cell membrane and enter the cytoplasm of target cells. Once inside the cell, they bind to specific receptor proteins in the nucleus or cytoplasm, which regulate gene expression and protein synthesis. Therefore, choice C is the correct answer.

Option A is incorrect because steroid hormones are not proteins, but rather lipid molecules derived from cholesterol.

Option B is incorrect because steroid hormones can diffuse through the cell membrane easily.

Option D is incorrect because steroid hormones do not act through second messenger cascades, instead, they directly bind to specific receptor proteins in the nucleus or cytoplasm.

Option E is incorrect because steroid hormones are transported in the bloodstream bound to specific carrier proteins, not dissolved in the plasma.