Lipids
Lipids: Organic molecules that are insoluble in water eg. Fats and oils.
(Fats are solid at room temperature and oils are liquid)
Esters formed by fatty acids combining with an alcohol.
Fatty acids contain an acidic group –COOH, known as a
carboxyl group. The larger molecules have
long hydrocarbon tails attached to the acid
‘head’ of the molecule. The chain is normally
around 15 carbon atoms long. Carboxyl
group
Some fatty acids have a double carbon bond
and these are called unsaturated
(monounsaturated) because they do not
contain the maximum possible amount of hydrogen. They form
unsaturated lipids. Double carbond bonds make the lipids melt more
easily eg. Most oils are unsaturated. If there is more than one double
bond, the fatty aid is described as polyunsaturated.
Alcohols and esters
Alcohols are a series of organic molecules, which contain a hydroxyl
group, -OH, attached to a carbon atom. Glycerol is an alcohol with 3
hydroxyl groups and therefore 3 hydrocarbon tails. The reaction between
an acid and an alcohol is called an ester. The chemical link between the
acid and the alcohol is called an ester bond.
The –COOH group on the acid reacts with the –OH group on the alcohol to
form an ester bond, -COO-. This is a condensation reaction because water
is formed as a product. This process can be reversed by adding water
(hydrolysis).
Triglycerides
These are the most common lipids, including fats and oils. A glyceride is
an ester formed by a fatty acid combining with the alcohol glycerol.
Glycerol has 3 hydroxyl
groups and each one can
form a condensation
reaction with a fatty
acid. The final molecule
contains 3 fatty acid
tails and 3 ester bonds.
Lipids: Organic molecules that are insoluble in water eg. Fats and oils.
(Fats are solid at room temperature and oils are liquid)
Esters formed by fatty acids combining with an alcohol.
Fatty acids contain an acidic group –COOH, known as a
carboxyl group. The larger molecules have
long hydrocarbon tails attached to the acid
‘head’ of the molecule. The chain is normally
around 15 carbon atoms long. Carboxyl
group
Some fatty acids have a double carbon bond
and these are called unsaturated
(monounsaturated) because they do not
contain the maximum possible amount of hydrogen. They form
unsaturated lipids. Double carbond bonds make the lipids melt more
easily eg. Most oils are unsaturated. If there is more than one double
bond, the fatty aid is described as polyunsaturated.
Alcohols and esters
Alcohols are a series of organic molecules, which contain a hydroxyl
group, -OH, attached to a carbon atom. Glycerol is an alcohol with 3
hydroxyl groups and therefore 3 hydrocarbon tails. The reaction between
an acid and an alcohol is called an ester. The chemical link between the
acid and the alcohol is called an ester bond.
The –COOH group on the acid reacts with the –OH group on the alcohol to
form an ester bond, -COO-. This is a condensation reaction because water
is formed as a product. This process can be reversed by adding water
(hydrolysis).
Triglycerides
These are the most common lipids, including fats and oils. A glyceride is
an ester formed by a fatty acid combining with the alcohol glycerol.
Glycerol has 3 hydroxyl
groups and each one can
form a condensation
reaction with a fatty
acid. The final molecule
contains 3 fatty acid
tails and 3 ester bonds.
