CHEMICAL STRUCTURE

Steroids are a class of lipids, which means they are insoluble in water but soluble in organic solvents. They all share a common main structure consisting of four fused rings of connected carbon atoms. These include three cyclohexane rings consisting of six carbon atoms, and one cyclopentane ring consisting of five carbon atoms, yielding seventeen in total. These 17 carbons atoms are numbered to help describe differences in steroid structures. Seemingly subtle changes at just a couple of the carbon positions can yield vastly different steroids. Cholesterol, from which all other steroids are derived, comes equipped with a hydrocarbon tail off its 17th carbon atom. This is removed when cholesterol is converted into either testosterone or oestrogen. Despite these two steroids controlling vastly different cell behaviours, structurally they are very similar and differ at only four carbon positions.