Mechanism of Steroid Hormone Action

How do hormones work? Hormones influence the growth and develop of organisms. For example hormones determine whether individuals become male or female. Many hormones are steroids. Steroids are a class of lipids. All steroids share a carbon skeleton composed of four fused rings. Hormones are compounds used for long distance signaling in both plants and animals. In animals, specialized cells produce hormones and release them into the circulatory system. Hormones travel to target cells in other parts of the body and cause a variety of changes in the target areas. Changes caused by hormones include changes in gene expression in target cells as well as Steroid hormones are soluble in lipids and can easily pass through cellular and nuclear membranes. In contrast, many other hormones are water soluble. Steroid hormones typically act by affecting gene expression while water-soluble hormones usually act by causing changes in biological processes in the cytoplasm of cells.

View the animation below, then complete the quiz to test your knowledge of the concept.


1	Steroid hormones bind to

		A)	carbohydrate receptors on the cell membrane of the target cell.
		B)	carbohydrate receptors in the cytoplasm of the target cell.
		C)	protein receptors on the cell membrane of the target cell.
		D)	protein receptors in the cytoplasm of the target cell.
		E)	protein receptors in the cytoplasm or nucleus of the target cell.

2	The steroid hormone-receptor complex binds to

		A)	hormone response elements in DNA.
		B)	hormone response elements in mRNA.
		C)	hormone response elements on proteins.
		D)	ribosomes to stimulate translation.
		E)	the cell membrane thereby increasing its permeability.

3	The mode of action of steroid hormones involves

		A)	a second messenger.
		B)	modification of enzyme activity.
		C)	stimulation of DNA replication.
		D)	stimulation of mRNA transcription.
		E)	inhibition of protein synthesis.

4	Steroid hormones travel in the blood attached to protein carriers.

		A)	True
		B)	False

5	Steroid hormones are water-soluble.

		A)	True
		B)	False

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