Flashcards in Chapter 6 Terms Deck (12):
Two molecules that have been derived from a common ancestor.
Homologs that are present within one species and often differ in their detailed biochemical functions.
Homologs that are present within different species and have very similar or identical biochemical functions.
Two sequences that are systematically aligned with respect to each other to identify regions of significant overlap.
Replacing one amino acid with another that is similar in size and chemical properties.
Describes a scoring system for the replacement of any amino acid with each of the other 19 amino acids. A large positive score corresponds to a substitution that occurs relatively frequently, whereas a large negative score corresponds to a substitution that occurs only rarely.
Yields a list of sequence alignments, each accompanied by an estimate giving the likelihood that the alignment occurred by chance.
A map of conserved residues that are structurally and functionally important ad are characteristic of particular families of proteins, which makes it possible to recognize new family members that might be undetectable by other means.
Proteins derived from common ancestors.
The process by which very different evolutionary pathways lead to the same solution.
Aligned sequences can be used to construct this "map" in which the length of the branch connecting each pair of proteins is proportional to the number of amino acid differences between the sequences.