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There are many different classes of lipids , such as fatty acids , triacyglycerols , phospholipids , steroids and glycolipids. Fats are solid at room temperature and oils are liquids at room temperature , this is because fats contain saturated hydrocarbon chains whereas oils contain unsaturated hydrocarbon chains , meaning that there is at least one carbon to carbon double bond In the chain. Fats are very important and have many different functions and properties , they are a source of energy , giving nine kilocalories per gram , they are an energy reserve meaning that any extra energy derived from food is stored as fat , they can provide insulation and protection to internal organs.


Saturated fats are fats which contain no double bonds , therefore all the carbons atoms are bonded to bonded to hydrogen atoms. Saturated fats contain long straight chains  , they are solid at room temperature and are mostly animal fats.Image


Unsaturated Fats have carbon to carbon double bonds . they are found in plants and fish , and vegetable based oils , they are liquid at room temperatures and their structures contain kinks caused by the double bonds.




Naturally occurring fatty acids are found to have even numbers of carbons, and the double bonds are in the cis form. It must also be noted that the presence and number of carbon doubles decreases the melting point. This is why if u take a tub of butter that claims to contain no saturated fats , meaning it only contains unsaturated fats , and leave it at room temperature you would find it turns into an oily , greasy pool inside in the tub, hence this why manufacturers of butters and margarines made of unsaturated fats put a disclaimer on the tub saying , keep refrigerated.


Non essential fatty acids are fatty acids which our body can synthesize and are therefore not required to come from our diet , alternatively essential fatty acids are fatty acids which cannot be synthesized in the body and must come from our diet. Some examples of essential fatty acids are omega-6 linoleic acid and omega-3 alpha-lenoleic acid.




The iodine index is used as  the degree of unsaturation and can be found by measuring the amount of iodine that reacts with the unsaturated fat or oil.




Pictures taken from

1)      The BIOCHEMJM Youtube channel