Evolution of the genomic systems of prokaryotes and its momentous consequences.

The earliest self-reproducing cell on Earth, our common ancestor, was probably as small as present-day bacteria. It gave rise to a very large and durable clone whose descendants must have been the only living occupants of the oceans for about one thousand million years. They reached astronomical numbers of separate, disjunct cells, and synthesized many new genes.

A powerful bacterial world.

Bacteria (prokaryotes) were the sole form of life on earth for some two billion years--roughly half its history. During this time they evolved into a giant, global superorganism and developed a remarkable mechanism for the creation and exchange of genetic material. Apart from its intrinsic interest, this has practical significance, for example in the development of multiple resistance to antibiotics of pathogenic bacteria such as those of tuberculosis.

Bacterial viruses, prophages, and plasmids, reconsidered.

Prophages and plasmids offer to the bacterial cells generalized access to each other's genes. The result is an extremely rich, available gene bank. It has successfully supported the original bacterial life since its beginnings and therefore it has conditioned all bacterial cells.