SUMMARY: To mimic the conditions on comets or space clouds, the gas mixture beamed in this experiment was a mixture of: water, methanol, ammonia, methane, and pyrazine. Pyrazine is an isomer of pyrimidine (both have the chemical formula C4H4N2). This gas mixture was cooled to 15-20K in a low pressure chamber and beamed with UV photons. Different ratios of this gas mixture was used as well as one mixture that did not contain methane. Molecules that are precursors to uracil and cytosine were found in the products as well as uracil itself. The mixture without methane also produced cytosine.
LESSON COMMENTS: Good questions that come out of this article are: what is the structure of cytosine and why does taking out methane lead to its production? What do the products (Figure 3) have in common with the molecules in the gas mixture? What is the next step in this research? Students can predict what the next experiment in this pyrimidine series will look like.
Nuevo, M., Materese, C. K., & Sandford, S. A. (2014). The Photochemistry Of Pyrimidine In Realistic Astrophysical Ices And The Production Of Nucleobases. The Astrophysical Journal,793(2), 125. doi:10.1088/0004-637x/793/2/125