Endosymbioses have dramatically altered eukaryotic life, but are thought to have negligibly affected prokaryotic evolution. Here, by analysing the flows of protein families, I present evidence that ...

Every living organism falls into one of two groups: eukaryotes or prokaryotes, with cellular structure determining which group an organism belongs to. Prokaryotes are unicellular and lack a nucleus ...

While prokaryotic cells do not have membrane-bound structures, they do have distinct cellular regions (Figure 1). In prokaryotic cells, DNA bundles together in a region called the nucleoid. Primitive ...