The presence of evolutionary traces is because some of the residues that perform key functional and structural roles tend to be preserved by natural selection; other residues that may be less crucial for structure and function tend to mutate more frequently.

Pairwise Sequence Alignment (PSA) is used to identify regions of similarity that may indicate functional, structural and/or evolutionary relationships between two biological sequences (protein or nucleic acid).

Topics include: Sequence Homology Versus Sequence Similarity and Identity, Methods, & Statistical Significance of Sequence Alignment.

Related Test: Bioinformatics Practice Test Questions: Sequence Alignment