2015/05/06 by Ben K. D. Pearce, Ralph E. Pudritz · 2 citations
Chemistry · Environmental Science · Physics and Astronomy · #Astro and Planetary Science #Astrobiology #Biochemistry #Biology #Chemical Analysis and Environmental Impact #Chemistry #Chondrite #DNA #Meteorite #Murchison meteorite #Nucleobase #Origins and Evolution of Life #Thymine #Uracil #astro-ph.EP
paper · pdf · doi:10.1088/0004-637x/807/1/85
published as 2015, ApJ, 807, 85 · 11 pages, 4 figures, accepted for publication in ApJ
arxiv created 2015/05/06 · openalex publication_date 2015/07/02 · arxiv updated 2015/07/06 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Carbonaceous chondrites are a class of meteorite known for having high contents of water and organics. In this study, the abundances of the nucleobases, i.e., the building blocks of RNA and DNA, found in carbonaceous chondrites are collated from a variety of published data and compared across various meteorite classes. An extensive review of abiotic chemical reactions producing nucleobases is then performed. These reactions are then reduced to a list of 15 individual reaction pathways that could potentially occur within meteorite parent bodies. The nucleobases guanine, adenine, and uracil are found in carbonaceous chondrites in amounts of 1–500 ppb. It is currently unknown which reaction is responsible for their synthesis within the meteorite parent bodies. One class of carbonaceous meteorite dominates the abundances of both amino acids and nucleobases—the so-called CM2 (e.g., Murchison meteorite). CR2 meteorites (e.g., Graves Nunataks) also dominate the abundances of amino acids, but are the least abundant in nucleobases. The abundances of total nucleobases in these two classes are 330 ± 250 and 16 ± 13 ppb, respectively. Guanine most often has the greatest abundances in carbonaceous chondrites with respect to the other nucleobases, but is 1–2 orders of magnitude less abundant in CM2 meteorites than glycine (the most abundant amino acid). Our survey of the reaction mechanisms for nucleobase formation suggests that Fischer–Tropsch synthesis (i.e., CO, H 2 , and NH 3 gases reacting in the presence of a catalyst such as alumina or silica) is the most likely candidate for conditions that characterize the early states of planetesimals.