Origins

Toadstools, people, plants, and amoebae have strikingly similar cells. All these organisms keep their DNA coiled up in a nucleus. Their genes are interspersed with chunks of DNA that cells have to edit out to make proteins. Those proteins are shuttled through a maze of membranes before they can float out into the cell. And these cells all manufacture fuel in compartments called mitochondria.

All species with this arrangement are known as eukaryotes. The word is Greek for “true kernel,” referring to the nucleus. All other living things that lack a nucleus and mitochondria are known as prokaryotes. “It’s the deepest divide in the living world,” says William Martin of the University of Düsseldorf in Germany.

In this month’s Origins essay, Carl Zimmer looks at the evolution of the eukaryotic cell, one of the most important transitions in the history of life. Indeed, when you look at the natural world, most of what you see are these “true kernel” organisms.

Much of what we have learned about eukaryotes comes from studying their cell biology and their genomes. Through these efforts, researchers have made tremendous advances in the past 20 years in understanding that eukaryotes represent the merging of primitive microbes from both the archaeal and the bacterial worlds.

In addition to the essay, Zimmer talks about eukaryotes in a podcast.

—Elizabeth Pennisi

Image: Katharine Sutliff