Size of the Minimal Genome

How many genes does it take to be alive? In humans, it certainly takes more than one, but probably less than 25,000. Basic life forms such as bacteria may require twice as many “minimal genes” as previously thought.

By knocking out genes one at a time from a microbe’s genome, scientists identify which of the genes cause death and total them up for the minimal genome. But microbes are a little more complex than realized and are able to compensate for missing genes with back-up genes that can manufacture the proteins needed to keep the organism alive.

The novelty of these kinds of studies is undeniable. But more interestingly, genes that have been identified as being indispensible to life could hold the key to longevity or other critical physiologic functions.

BBC News, April 3, 2006