| Term | Description | SeeAlso |
| Wild-Type | The genetic term for "normal" or reference strain. When a geneticist crosses (breeds) a mutant individual with a normal individual, the geneticist says that she has made a cross between a mutant and a wild-type. | Genetics, Mutant, Test Cross |
| Works in Cis | Works on the same chromosome. For example, the Lac operator site only affects Lac genes on the same chromosome (rather than making a protein). | Lac Operon, In Trans |
| Works in Trans | Works across chromosomes. If a diploid genome has a mutant in one of its chromosomes, a wild-type gene in the homologous chromosome can compensate for the mutation | In Cis |