Elements: C, H, and O.
Function: Storage, cushion, hormones.
Fatty acids are lipids that are made from long chains of methyls. Fatty acids can be either saturated, where the chain only has groups of CH2, or fatty acids can be unsaturated, where there are one or more CH = CH groups, carbons attached with a double bond to another carbon. Think of the fatty acids as being unsaturated with H, since to form a double bond, two carbons must lose H. So saturated fatty acids are saturated with H, and unsaturated fatty acids have room for more H atoms. At room temperature, saturated fatty acids are waxy solids, and unsaturated fatty acids are liquid. Below are two 18C fatty acids, stearic acid and oleic acid. They differ only in that stearic acid is saturated with H, while oleic acid is an unsaturated fatty acid.
Common Fatty Acids
Triglycerides, or fats, have the simplest form of all lipids. In plants, triglycerides form the major proportion of lipids in plants. In animal, adipose cells (fat cells) stores triglycerides for future use as energy. Triglycerides are made from three chains of fatty acids, bonded to a pole of glycerol. In the molecular formula below, the R-group represents fatty acids, where they can either be all different, be the same, or only two fatty acids be the same.
Essential Fatty Acids:
Just as there are essential amino acids that our bodies can not synthesis, there are also essential fatty acids, like linoleic acid, that our body has to get our from food. We can easily make saturated fatty acids and unsaturated fatty acids that have one double bond, but we do not have the proper enzymes to synthesis unsaturated fatty acids that have more than one double bond. These fatty acids are very important to our immune system and to help us regulate our blood pressure, for they are used to make essential compounds, such as prostaglandins. Prostaglandins are a group of organic molecular messengers that changes our blood pressure, open air passages, and cause uterine contraction.