Alternative definition : CRCH: A class of hydrocarbons formed from units of isoprene (C5H8) linked to form
chains or rings. A mono-terpene has 2 isoprene units, a sesquiterpene has 3 isoprene
units, a diterpene has 4 isoprene units, a sesterpene has 5 isoprene units, a triterpene
has 6 isoprene units, a carotenoid has 8 isoprene units, and rubber has 100 isoprene
units.;