Fats and Fatty Acids

Each tiny molecule is comprised of a fatty chain at one end and an acid (carboxyl) group at the tail. Every glycerol molecule is hydrophilic or water-soluble while the fatty acid end is hydrophobic or water insoluble. The fatty chain is built upon carbon, hydrogen, and a methyl (-CH3) group at the end. These properties will prove important for fat function within our body.

Fats and fatty acids will be unique based on two parameters: the length of the overall fatty acid chain and in what configuration it resides. Let's first touch on length (and structure of bonds within the fatty acid).

The length is determined by how many carbon atoms are in the chain and the number of carbon atoms present help name the fat. This fact is useful by scientists to distinguish where chemical reactions are taking place. A side comment about numbering. There are two ways to count carbon atoms. We will use the omega numbering system which counts atoms from left to right similar to the way we read English. The other way is called delta numbering and goes from right to left.

At each carbon atom, multiple types of bonds may be formed. These include both single and double bonds. Carbon bonded by single bonds will make the fatty acid saturated and generally inert/stable. The double bonds in these fats produced unsaturated fatty acids and ultimately change the physical and chemical properties. One double bond creates monounsaturated, while two or more creates a polyunsaturated fat.

The other distinction is the spatial fat and fatty acid configuration. Fatty acids can exhibit cis or trans configurations which describes how fats fold. A cis configuration is bent. The feature occurs because hydrogen atoms at the double bond site are on the same side. Each hydrogen atom repels the other forming a kink. The other special arrangement (trans) occurs when hydrogen atoms are across from one another at the double bond site. This effectively straightens the fatty acid and makes it behave like a sat fat similar to those of shortenings and margarines.

The differences in length, bond types, and spacial arrangement change how fats interact within our body. Properties like melting point and freezing point change.