The principle, proposed by A. Weismann, that hereditary information flows only from genome to soma, not vice versa; the principle would be flouted were Lamarckism true. In its refined, modern form, the principle reads that information flows always from DNA to RNA to protein, and not back again. An enzyme, reverse transcriptase, is now known that does allow information to flow from RNA to DNA, and a category of viruses (retroviruses) do insert their genetic component into their hosts’ DNA by this means. Some genes (virogenes) appear to be of viral origin.
Subjects: Ecology and Conservation — Zoology and Animal Sciences.