Gene: a stretch of DNA that can be transcribed into a functional RNA molecule. This RNA molecule is frequently, though not always, translated into a protein. Genes are always referred to as “functional units of inheritance”, which is not a fantastically intuitive concept.
This one was given to us by a German who used the Greek root “genea” which means “birth” or “race”. It’s the same root that prefixes “generation” and “genesis”.
Misconception: it is dangerous to talk of someone as “having” or “not having” the gene for Huntington’s disease. While it is true that someone with the disease has a different “form” of the gene than a healthy individual and that the two individuals could technically be said to have different genes, this type of phrasing perpetuates the meme that people with inherited conditions have an extra gene that healthy individuals don’t have. It would be less ambiguous to talk of having or not having a mutation in such a gene: “I want to get tested to know if I have a mutation in the gene associated with Huntington’s disease” as opposed to “I want to get tested to know if I have the gene for Huntington’s disease”.
The concept of the “gene” is still evolving. It used to be one gene led to one RNA molecule led to one protein. Now, however, scientists speak of “microRNA genes”, which are stretches of DNA that code for a functional RNA molecule that is never used to make a protein, so the gene-protein marriage is no longer entirely true.