||Supplementary Materials p.1 left column bottom paragraph:"Genome replication in free-living organisms requires the synthesis of new nucleotide triphosphates to create two new double helices from the parental DNA molecule. Such synthesis involves the use of PRPP (phosphoribosyl pyrophosphate) and amino acid molecules, which
[investigators] assume must first also be synthesized, as well as additional investments of ATP in various steps in the
purine and pyrimidine biosynthetic pathways. These
pathways are generally conserved across the Tree of Life,
and the total biosynthetic costs can be derived from the cumulative investments in each pathway step [supplementary refs 2, 3]. Using the costs (in ATP) for PRPP and individual amino acids outlined by Akashi and Gojobori [primary source] for a starting point of glucose, the biosynthetic costs are estimated to be: 51.7 P for dATP, 48.7 P for dCTP, 52.7 for dGTP, and 47.7 for dTTP. Similar estimates were presented by Wagner [supplementary ref 5]. Given the similarity of all four values, for the purposes herein, it will be sufficient to approximate the biosynthetic cost of each dNTP as 50 P."