These are called the linolenic and linoleic acid series respectively. The double bonds in biological fatty acids are always separated by one saturated carbon. Since they do not dissolve in water, they have no water of hydration. Glycogen is a branched, glucose animal starch. Simple sugars are excellent cellular caloric sources.
Nerve cells can only utilize glucose as an energy source.
Sugars may also be attached to proteins as glycoproteins and may act as receptors on cell membranes. The sequence of amino acids is determined by the genetic code. The genetic code codes for only 20 different amino acids. There are a few proteins that animals use that contain amino acids other than the 20 that are coded for. This means that these amino acids must be converted from one of the twenty while they are on the protein.