Transcript LIPIDS - A level biology

LIPIDS
As
Introduction
Lipids are fats and oils, which are important sources
of energy in the diet . They have other uses as well. Energy is
stored in the body as fat. As well as being an important
energy store, the fat stored under the skin of mammals is an
important insulation layer which helps to keep the body
warm. Lipids are also important in the structure of cell
membranes.
Forming lipids from glycerol and
fatty acids
Lipids are made from glycerol and fatty acids bonding by a
condensation reaction this reaction is reversible via hydrolysis.
H
H
H - C- OH
H - C- OH
H - C- OH
O
+
Condensation
C - R*
OH
H - C - O - C - R^
H - C - OH
Hydrolysis
H - C - OH
H
* R group made up of a hydrocarbon chain
O
H
^ can be more saturated
+ H2O
Saturated or Unsaturated
Carbon atoms can bond with other carbon atoms to
form a carbon-carbon bond.There are lots of these bonds in
fatty acid molecules. Sometimes there is a double bond
between 2 carbon atoms in a fatty acid. If all of the carboncarbon bonds in he R group are single bonds , the fatty acid
is said to be SATURATED. However if some of the carboncarbon bonds are double bonds, the fatty acid is said to be
UNSATURATED. See next page for pics.
This shows the structural differences between a saturated
fatty acid (top), monounsaturated fatty acid (middle), and
polyunsaturated fatty acid (bottom).
Triglycerides
Triglycerides that contain long, Saturated Fats tend to
form hard fats like lard + butter, which are solid at room
temperature. Triglycerides that contain shorter unsaturated fatty
acids are called Unsaturated Fats. They rend to form oils
which are liquid at room temperature like sunflower oil or olive
oil.
Phospholipids
Phospholipids are a special type of lipid ;
• They have 2 fatty acid chains
• These form a tail which is Hydrophobic ( water hating )
• The phosphate group is Hydrophillic ( water loving )