13 - Minimal and Ancestral Genomes

Abstract

This chapter provides a reconstruction of two types of genetic systems that may seem similar, and are often discussed together, but that are in fact quite different. One is ancestral genome, which is the inference of the genetic makeup of a common ancestor of two or more contemporary genomes. The other construct is minimal genome, which is the smallest gene set capable of sustaining itself. Genes and genes product of the existing species are compared and infer the set of genes that their ancestor had (what the ancestor was), as well as the process that is required to transform this ancestor into the currently living species. The second construct requires more explanation. Minimal genome is an object of genetic engineering, or synthetic biology. Most often, the minimal genome approaches assume two things:first, a minimal genome that sustains a modern-type cell and second, the minimal cell is supplied with nutrients that one defines himself or herself. The minimal genome is also relative, in the sense that not all its genes are required under all growth conditions A computer is used to put together the list of genes that are expected to enable functioning of minimal genome but the proof of minimality has to come from the lab.