— with hydrogen atoms: there are no double
bonds between carbon atoms, so each carbon
within the chain is bonded to two hydrogen
atoms. An unsaturated lipid has one or more
double bonds between carbon atoms along its
backbone. The double-bonded carbons
therefore have only one bond left for a
hydrogen atom. A fat molecule with more
than one double bond is called
polyunsaturated.
Fats and fatty acids. Fatty acids are mainly
chains of carbon atoms, shown here as black
dots. (Each carbon atom has two hydrogen
atoms projecting from it; the hydrogen atoms
are not shown.) A fat molecule is a