Fatty acids are long chain hydrocarbons with a carboxyl group on one end (thus the acid designation).
They can differ with respect to the number of carbons in the hydrocarbon region and degree of saturation. Palmitic acid has 15 hydrocarbon residues while stearic acid has 17.
The degree of saturation refers to the presence or absence of C=C double bonds in the hydrocarbon region. Both steraric acid and oleic acid have 17 carbons in the hydrocarbon region but oleic acid has one carbon=carbon double bond and is therefore considered an unsaturated fatty acid while stearic acid has only singe C-C bonds and is considered a saturated fattry acid.
The presence of the C=C double bond gives the hydrocarbon region a distinct bend whereas the saturated fatty acid has a linear appearance.
Which of the following fatty acids is saturated? Which has one C=C double bond? Which has one double bond and which has no double bonds? Which fatty acid is a polyunsaturated fatty acid?