omologhi

Omologhi is an Italian term used in science to describe entities that are related by homology. In biology and chemistry, the word covers two related but distinct ideas: homologous genes or proteins, and members of a homologous series of compounds.

In biology, omologhi denotes genes or proteins that are related by descent from a common ancestral sequence. They are identified by sequence similarity and evolutionary conservation. Within a genome, homologs can be classified as orthologs—genes in different species that originated by speciation and retain the same function—and paralogs—genes related by duplication within a genome that may diverge in function. Comparing homologs across species allows inference of gene function, evolutionary relationships, and conserved biological pathways. Prominent examples include the HOX gene family, whose homologs are found across animals and regulate body plan development.

In chemistry, omologhi refers to members of a homologous series—compounds that differ from each other by a repeating unit, typically a CH2 group. Members share common functional groups and similar chemical properties, enabling systematic prediction of properties such as boiling points and solubility. Classic examples are the alkane series (methane, ethane, propane, butane...), the alcohol series (methanol, ethanol, propanol...), and the carboxylic acid series (formic acid, acetic acid, propionic acid...). The concept of homologous series is used to organize compounds and study trends in physical and chemical behavior.