Subject:The world of fats
1. What are fats?
Fats are one of the three main macronutrients, others being proteins and carbohydrates.
Fats and cholesterol are examples of lipids that we have in our bodies. Lipids are molecules that are
not soluble in water, because of their non-polar structure. Water is a polar molecule so there is less
attraction between water and non-polar molecules.
Fats are esters that are formed from glycerol and 1 to 3 fatty acids.
Fatty acids are long carbohydrate molecules, that have a carboxyl group at the end of the carbon
chain. Even though the carboxyl group is a polar group, the long carbon chain of the fatty acid makes
the molecule non-polar.
Steraic acid is a saturated fatty acid
Triglycerid has three fatty acids
Depending on the amount fatty acids attached to a fat, fats are listed into three categories: mono-, di-,
and triglycerides. The fats in our body are most commonly triglycerides.
Fatty acids can be either solid or liquid at room temperature. The chemical reason for this is in the
structure of their molecules. Saturated fatty acids, which are solid at room temperature, have only a
straight carbon chain, with only single bonds between the carbon atoms. Unsaturated fatty acids
have at least one double or triple bond located somewhere in the long carbon chain. This gives the
molecule a bend in its chain. The weak forces between molecules are stronger on straight molecules
than bended ones, and the stronger the force between the molecules, the lower the melting point of
that substance is. This makes saturated fatty acids solid and unsaturated fatty acids liquid.
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