Homology can be defined as the presence of common structures because of shared ancestry. Homology can involve genes, proteins, or anatomical structures. As a result of 'descent with modification,' many homologous structures have adapted different purposes. Under what circumstances might one expect proteins of similar function to not share homology? Would you expect such proteins to be homologous at the level of DNA sequences?

Key Concepts

Homology

Homology refers to the similarity in structures or sequences that arises from a common ancestor. In genetics, this can pertain to genes, proteins, or anatomical features that have evolved from a shared lineage. Understanding homology is crucial for studying evolutionary relationships and functional similarities among organisms.

Convergent Evolution

Convergent evolution occurs when different species independently evolve similar traits or functions due to similar environmental pressures, rather than from a common ancestor. This can lead to proteins that perform similar functions but do not share a homologous relationship at the genetic level, as they arise from different evolutionary paths.

Molecular Homology vs. Functional Homology

Molecular homology refers to the similarity in DNA, RNA, or protein sequences due to shared ancestry, while functional homology pertains to similarities in the roles or functions of these molecules. It is possible for proteins to exhibit functional homology without molecular homology, especially if they have evolved independently to perform similar tasks in different organisms.