Steroid hormones have how many hydrocarbon rings?

• A. 4 hydrocarbon rings
• B. 3 rings
• C. 5 rings
• D. 2 rings

Answer: (A)

Steroid hormones have a four-ring core. This backbone is a fused system made up of three six-membered rings and one five-membered ring, all connected in a rigid four-ring framework. This structure comes from cholesterol and gives steroids their characteristic shape and hydrophobic, membrane-permeable properties, which in turn relate to how they interact with intracellular receptors rather than surface receptors. Because every steroid hormone shares this four-ring core, the correct idea to recall is that the steroid backbone comprises four hydrocarbon rings.