Structure of Lipids

Lipids are a group of hydrophobic molecules that include triglycerides, which are used to store energy, and phospholipids, which are the major structural components of cell membranes.

Triglycerides and most phospholipids consist of glycerol and fatty acid chains.

Fatty acids have methyl groups at one end of the chain and carboxyl groups on the opposite end. The carbon connected to the carboxyl group is called the alpha carbon, and the methyl group carbon is known as the omega carbon.

Fatty acids vary in length and the presence of double bonds in the hydrocarbon chain. Those with double bonds are unsaturated fatty acids and those with only single bonds are saturated fatty acids because they are saturated with the largest number of hydrogen atoms possible.

Fatty acids often have common names but can be systematically named according to the number of carbon atoms and the number and position of the double bonds in the carbon chain.

There are several common numbering methods. The carboxyl referencing system counts the position of all the double bonds from the carboxyl carbon, which is numbered as 1. The omega referencing system counts the position of the double bond closest to the omega