In with three fatty chains connected by


In the body, some of the important molecules use
cholesterol as a building block so start from like bile acids and steroid
hormones which includes sex hormones.  It
is vital for the synthesis of vitamin D, which happens in the liver and cells,
and is obtained from your diet, and transported around your body by the blood
stream, and is also hydrophobic so it is insoluble.


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Wax is highly insoluble, and at room temperature,
is more solid than oils.  It also
provides a waterproof layer that prevents water loss, and because it has
hydrophobic properties, it stops water from being absorbed.



Lipids provide the
body with nine calories per gram, making them the most energy rich component of

Did you know…


One fatty acid chain is replaced by a phosphate
base group which makes the head of the molecule soluble in water (Hydrophilic),
but the tails of the molecule are still insoluble in water (Hydrophobic), this
is known as an amphipathic molecule.  The
main component of the cell membrane is a phospholipid.  It is made up of a glycerol molecule and a phosphate
group, and form a double layer when many of them join up.  (Biology Dictionary (2017)


A glycerol molecule with three fatty chains
connected by covalent bonds, and are known as an ester bond which are formed
when a condensation reaction occurs. 
Each triglyceride contains a carboxylic acid group which can be found at
the terminal carbon atom and are normally made of around 14-22 carbons long.  They are hydrophobic which means they are
insoluble in water.  To prevent the
hydrogen bonds forming with the water molecules, the charges are distributed
evenly around the molecule. (A-Level
notes 2016)


As opposed to saturated fatty acids, unsaturated
fatty acids contain some double bonds. 
If only one double bond is present, it is known as monounsaturated, but
if more than one double bond can be found, then it is known as
polyunsaturated.  At room temperature,
fats with unsaturated tails are normally found as liquids which makes it
difficult for them to pack together tightly. 

Unsaturated fatty acids

A saturated fatty acid is composed of a chain
consisting of hydrogens and carbons connected by single bonds, and can be most
commonly found in the length of 18 bonds that can mainly be found in foods, and
at room temperature, is usually solid. 
(Mclaughin, 2017)

Saturated fatty acids

Lipids are a high energy source that are required for the
absorption of fat soluble vitamins. 
There are two main types of lipids; simple lipids and complex
lipids.  They are not soluble in water so
are known as hydrophobic, but are soluble in organic solvents like alcohol and
acetone.  Lipids also act as an
insulating layer under the skin to help keep the body warm.  Lipids are made from hydrogen and carbon
which gives them the name hydrocarbons.  “When metabolized, lipids are oxidized to release large amounts of
energy and thus are useful to living organisms Lipids are molecules that can be
extracted from plants and animals using nonpolar solvents such as ether,
chloroform and acetone” (Mandal, 2012)