EVOLUTION STUDIED USING PROTEIN STRUCTURE
One of the principle goals of evolutionary biology is to generate phylogeny that best represents the evolutionary histories of all organisms on earth. Aside from directly investigating the fossil records of ancestor species, all phylogenetic methods depend on the comparison of specific features (homologous characteristics) of contemporary organisms to determine the evolutionary relationships between different organisms. Among the features are morphological, physiological, genetic, and genomic which changed as the organisms evolved. The study of evolution changed dramatically with the discovery of DNA and the evolutionary fingerprint it represents. Evolutionary relationships between organisms can be studied by comparing their DNA sequences (Zuckerkandl and Pauling, 1965). Gene mutation is the primary cause of evolution, so utilizing the universal carrier of genetic information as the characteristic by which phylogenetic comparison is made makes sense. This approach has significant advantages over the classical approach in which morphological and physiological characteristics are used. This is exemplified by the discovery of a third branch of life, the archaea, which have no substantial morphological or physiological differences to other prokaryotes. Archaea were discovered to be a separate domain of life by analyzing small subunit ribosomal RNAs (SSU rRNA) (Woese and Fox, 1977).
While studying ...