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Chapter 25
The Organic Chemistry of Lipids
Important Terms
angular methyl group
a methyl substituent at the 10- or 13-position of a steroid ring system.
carotenoid
compounds responsible for the red and orange colors of fruits, vegetables, and fall
leaves.
cholesterol
a steroid that is the precursor of all other steroids.
detergent
a sodium or potassium salt of a benzenesulfonic acid.
dimethylallyl
a precursor needed for the biosynthesis of terpenes, which is biosynthesized
pyrophosphate
from isopentenyl pyrophosphate.
diterpene
a terpene that contains 20 carbons.
fat
a triester of glycerol that exists as a solid at room temperature.
fatty acid
a long straight-chain carboxylic acid.
hormone
a chemical messenger that stimulates or inhibits some process in target tissues.
isopentenyl pyrophosphate
the starting material for the biosynthesis of terpenes.
lipid
a water-insoluble compound found in a living system.
lipid bilayer
two layers of phosphoacylglycerols arranged so that their polar heads are on the
outside and their nonpolar fatty acid chains are on the inside.
membrane
the material that surrounds the cell to isolate its contents.
micelle
a spherical aggregation of molecules, each with a long hydrophobic tail and a
polar head, arranged so that the polar head points to the outside of the sphere.
mixed triacylglycerol
a triacylglycerol in which the fatty acid components are different.
monoterpene
a terpene that contains 10 carbons.
oil
a triester of glycerol that exists as a liquid at room temperature.
phosphatidic acid
a phosphoglyceride with one OH group of glycerol esterified with phosphoric acid.
phosphoglyceride
formed when two OH groups of glycerol form esters with fatty acids and the
(phosphoacylglycerol)
terminal OH group is part of a phosphodiester.
phospholipid
a lipid that contains a phosphate group.
polyunsaturated fatty acid
a fatty acid with more than one double bond.