There are also several classes of C-N bonds. There are many thousands of biologically synthesized amino acids, but only twenty are routinely found in proteins. The most common amide groups are the peptide bonds between consecutive amino acid residues in polypeptides. At cellular pH the monoprotonated, dianion HPO 4 -2 predominates. Fatty Acids Nucleotides 1.
Monosaccharides can form polymers like starch and glycogen .
These polymers contain linear segments and branched portions. They are storage compounds. In mammals the glycogen is mainly stored in the liver, with some in the muscles. Amino acids contain both an amine and a carboxylic acid group. They exist in an internally ionized form called a zwitterion.