6.3 Structure of Lipids
Chapter 6 ~ The Chemistry of Life
Section 6.3
p. 157 - 163
The Structure of Lipids
• Lipids are made
of two subunits:
– Glycerol
– Fatty acids
General structure of fatty acids:
a type of lipid
• Fatty acids are carboxylic acids with a long hydrocarbon tail. In
the general structure, "R" represents the large hydrocarbon
tail.
• R generally represents a hydrocarbon chain of 3 to 19 C atoms.
A fatty acid ~ myristic acid
• Fatty acids are carboxylic acids with a long hydrocarbon tail. In
the general structure, "R" represents the large hydrocarbon
tail. In this example, the hydrocarbon tail has 13 carbons.
• Myristic acid is in butterfat and coconut oil.
• It is a saturated fatty acid: the hydrocarbon tail has no double
bonds.
A fatty acid ~ oleic acid
• In this example, the hydrocarbon tail has 17 carbons.
• Oleic acid is in olive oil, peanut oil, and human fat.
• It is an unsaturated fatty acid: the hydrocarbon tail
has a double bond.
• Since there is only one double bond, the fatty acid is
monounsaturated.
• Saturated fats have all single bonds.
• Unsaturated fats have at least one
double bond.
Structure of glycerol, a compound
that reacts with fatty acids
• The -OH groups on
glycerol can react
with the -COOH
groups on fatty
acids, causing the
fatty acid to join to
the glycerol, and
releasing water.
• The glycerol and 3
fatty acids react to
form triglycerides.
Glycerol and fatty acids form
triglycerides
• The -OH groups on
glycerol can react
with the -COOH
groups on fatty
acids, causing the
fatty acid to join to
the glycerol, and
releasing water.
• The glycerol and
fatty acids react to
form triglycerides.
General formulas show how glycerol
and fatty acids form triglycerides
• The -OH groups on glycerol can react with the COOH groups on fatty acids, causing the fatty acid to
join to the glycerol, and releasing water.
• The glycerol and fatty acids react to form
triglycerides.
Structural formulas show how
glycerol and stearic acid forms
tristearin, a triglyceride
• The -OH groups on glycerol can react with the COOH groups on stearic acid, causing the stearic acid
to join to the glycerol, and releasing water.
• The glycerol and stearic acid react to form tristearin,
a triglyceride.