The amino acid sequence determines the structure and function of every protein. Changes in the amino acid sequence of a protein may thus have effects on the structure and function of that protein.
Proteins are vital for the development and survival of any living organism.
Any changes in the structure and function of a protein may, in turn, affect the function and development of an organism which uses this protein. When a change in protein structure or function enhances the ability of an organism to survive in its environment, this change is likely to be passed to future generations, and a small step in evolution occurs. In other words, evolution and the creation of new species may occur when proteins become altered and in turn alter the development and survival capabilities of living organisms. As a result, different organisms often have related, but not identical, protein sequences. In addition, with the advances in molecular biology and DNA sequencing technology, hundreds of thousands of genes have been sequenced and translated into protein sequences.