Passage I (Questions 1-7)

    Commercial food products will often have partially hydrogenated vegetable oil as one of the ingredients. Naturally occurring fatty acids such as vegetable oil are long carbon chain carboxylic acids. They can be hydrogenated to convert the alkyl chain into to an aliphatic R group. The fatty acids can be found as either the carboxylic acid or as part of a fatty acid triglyceride as shown below:


    The fatty acid is isolated when the fatty acid triglyceride is hydrolyzed. Three acids will be formed from every fatty acid triglyceride. The R group can be any alkyl group. In naturally occurring fatty acids, the R will have an odd number of carbons. Counting the acid carbon, natural fatty acids have an even number of carbons. This is attributed to fatty acid synthesis occurring two carbons at a time by in vivo  mechanisms. In the table below are some common fatty acids that are naturally found in animals:

Acid	Formula	pi
Arachidic	CH3(CH2)18CO2H	0
Arachidonic	CH3(CH2)4(CH=CHCH2)4(CH2)2CO2H	4
Behenic	CH3(CH2)20CO2H	0
Lauric	CH3(CH2)10CO2H	0
Lignocaric	CH3(CH2)22CO2H	0
Linoleic	CH3(CH2)4(CH=CHCH2)2(CH2)6CO2H	2
Linolenic	CH3CH2(CH=CHCH2)3(CH2)6CO2H	3
Myristic	CH3(CH2)12CO2H	0
Oleic	CH3(CH2)7CH=CH(CH2)7CO2H	1
Palmitic	CH3(CH2)14CO2H	0
Palmitoleic	CH3(CH2)5CH=CH(CH2)7CO2H	1
Stearic	CH3(CH2)16CO2H	0

    Vegetable oils generally have more unsaturation than animal fats. As the amount of unsaturation increases, the melting point of the fatty acid will decrease. For this reason, many animal fats are solids while many vegetable oils are liquids at room temperature. Fatty acids can play one of three roles in biological systems. They are found as the building blocks of cell walls as phospholipids and glycolipids. Fatty acids form derivatives that serve as hormones (intercellular messengers). Fatty acids are also used for fuel through fatty acid metabolism.