Back in the 20th century, a gene was such a simple thing: The lone carrier of inherited biological information, a single stretch of DNA that contained the code to create a single protein. But, as is so often the case in science, the more we’ve learned about genes, the more we’ve realized how much we don’t know.

As science writer Carl Zimmer explains in this morning’s New York Times, scientists are rethinking the whole notion of what a gene is, and how heredity works:

It turns out, for example, that several different proteins may be produced from a single stretch of DNA. Most of the molecules produced from DNA may not even be proteins, but another chemical known as RNA. The familiar double helix of DNA no longer has a monopoly on heredity. Other molecules clinging to DNA can produce striking differences between two organisms with the same genes. And those molecules can be inherited along with DNA.

Zounds!

This rethinking of DNA has gone along with a greater respect for the role of RNA, once considered a mere cellular stenographer. As it turns out, RNA plays a much more active role in the workings of the cell. Hence the drug industry’s intense interest in figuring out how to manipulate RNA for therapeutic purposes — a subject explored in this story from today’s NYT, and in Health Blog posts on RNA-driven companies such as Alnylam, Isis and Sirna (bought by Merck in 2006).

Zimmer Squared: Science writer Carl Zimmer’s dad is Dick Zimmer, a New Jersey Republican, who lost a bid for a U.S. Senate seat to incumbent Democrat Frank Lautenberg last week. The elder Zimmer told Scientific American that his son Carl helped shape his thinking on science issues, including stem cell research and the teaching of evolution.

DNA image via Wikimedia Commons