Those amino acids that are ionizable have R groups that become charged when in solution. How a polypeptide chain is formed and broken. This separates the molecules into individual amino acids. This bond is called a peptide bond. A long chain of amino acids linked by peptide bonds is a polypeptide.
Proteins are long, complex polypeptides.
The great variability possible in the sequence of amino acids in polypeptides is perhaps the most important property of proteins, permitting tremendous diversity in their structures and functions. This sequence determines the further levels of structure of the protein molecule resulting from bonds that form between these groups. Having the proper sequence of amino acids, then, is crucial to the functioning of a protein. If the protein does not assume its correct shape, it will not work properly or at all. Because different amino acid functional groups have different chemical properties, the shape of a protein may be altered by a single amino acid change.