Relaxed requirements: We demonstrate the formation of adenine, hypoxanthine, and guanine from heated (130 °C), UV-irradiated formamide solutions in the absence of an inorganic catalyst. Evidence is also provided that "classical" HCN pathways for purine nucleobase production are also active in heated and UV-irradiated formamide reactions. (Chemical Equation Presented) © 2010 Wiley-VCH Verlag GmbH& Co. KGaA

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Many high school laboratory experiments demonstrate concepts related to biological evolution, but few exist that allow students to investigate life’s chemical origins. This series of laboratory experiments has been developed to allow students to explore and appreciate the deep connection that exists between prebiotic chemistry, chemical evolution, and contemporary biological systems. In the first experiment of the series, students synthesize adenine, one of the purine nucleobases of DNA and RNA, from plausibly prebiotic precursor molecules. Students compare their product to authentic standards using thin-layer chromatography. The second and third experiments of the series allow students to extract DNA from a familiar organism, the strawberry, and hydrolyze it, releasing adenine, which they can then compare to the previously chemically-synthesized adenine. A fourth, optional experiment is included where the technique of thin-layer chromatography is introduced and chromatographic skills are developed for use in the other three experiments that comprise this series. Concepts relating to organic and analytical chemistry, as well as biochemistry and DNA structure, are incorporated throughout, allowing this series of laboratory experiments to be easily inserted into existing laboratory courses and to reinforce concepts already included in any high school chemistry or biology curriculum.

The cover picture shows a can of prebiotic soup for an improved "product", thanks to the addition of UV photons. On p. 1240 ff., N. V. Hud, T. M. Orlando and co-workers demonstrate that model prebiotic reactions with formamide as a source material produce a greater yield and diversity of purine nucleobases when formamide is irradiated with UV photons during heating, in the presence and absence of inorganic catalysts. Guanine is also observed for the first time in model prebiotic formamide reactions, as emphasized by the pasta shape. The observation that purine nucleobases are still formed in UV-irradiated/heated formamide solutions in the absence of inorganic catalysts (i.e., with "100 % less salt") further relaxes the requirements for obtaining nucleobases on the prebiotic Earth.