The Carbon atom has unique properties that make it ideal to the construction of biomolecules as carbohydrates, proteins and lipids. Carbon atoms can form covalent bonds to as many as four different atoms being an interesting atom to form the "skeletons" for macromolecules (as a "backbone structure" that will link the other diferential atoms from each biomolecule).
The individual structure of carbon atoms have an incomplete outermost electron shell, with six electrons and six prontons (two electrons in the inner shell and four in the out shell). It atomic structure making possible to form four covalent bonds with other atoms.
The hydrocarbons are important molecules that can form chains because the bonding patterns of carbon and hydrogen, being the "backbones" of most of the molecules essential for life.
Sweet potatos are a dish rich in carbohydrates that are one of the many molecules with a "backbone" of hydrocarbons.