Chemist’s Guide to Creating Life

With each passing summer, early autumn is heralded by a number of familiar signs: the leaves turning brilliant shades of yellows and reds, a reduction in the number of joggers on the Charles, and the announcement of the most prestigious awards in all of science, the Nobel Prizes. This year, the Nobel Prize in Physiology or Medicine was awarded to John B. Gurdon and Shinya Yamanaka for pioneering research in cellular reprogramming, which could be incredibly beneficial for medical treatments involving stem cells. The Physics Prize was granted to Serge Haroche and David J. Wineland ’70 for developing methods to directly observe quantum states of atoms and photons, which could revolutionize computing technology.

And while most Nobel Prize winners complete their research decades prior to winning their award, there are a number of compelling results being published each week. This past week, Dougal Ritson and John D. Sutherland of the University of Cambridge published a paper demonstrating that complex organic chemicals required for life can be generated using compounds as simple as hydrogen cyanide. Perhaps the most interesting unanswered scientific question in the universe after, “How was the universe created?” is, “How did organic life come to be?” Since the life we observe in nature is replicated from existing life, the question of abiogenesis—how complex, reproducible, organic systems were derived through simple chemistry—is non-trivial. The first major experiment to tackle this question was the Miller-Urey experiment in 1953.

Harold C. Urey, recipient of the 1934 Nobel Prize in Chemistry for his discovery of heavy water, and his graduate student Stanley L. Miller took on the problem of abiogenesis by attempting to simulate the early atmospheric environment. Their model contained a simple collection of gases, including water vapor, methane, ammonia, and hydrogen gas, in a simple glass setup containing a heater, a condenser, and an electrical spark to simulate the heating and cooling processes in the atmosphere, as well as the energy supplied by a natural event like lightning. Amino acids are the basic building blocks of the proteins that make up every known form of life. Of the 20 amino acids in our biology, 11 of them were identified by Miller and Urey, and later analysis of their experiment demonstrated that all 20 amino acids had in fact been found.

But there is much more to life than just proteins. The central dogma of molecular biology as coined by Francis H. C. Crick describes the flow of information in life proceeding from DNA, transcribed to RNA, and translated to the protein chains that make up most of life. While this is the general procedure of information transfer in living systems, there are a number of exceptions, and Crick later admitted that perhaps the word “dogma” was not the best term for the process. The breakthrough of Ritson and Sutherland, then, was in determining that compounds necessary for RNA, in addition to proteins, could be completely constructed from basic, inorganic compounds given standard environmental conditions.

Though there are several kinds of RNA, each RNA molecule consists primarily of a ribose sugar, a phosphate group, and a nucleotide base. Every sequence of three bases codes for a specific amino acid. In a 2009 paper, Sutherland’s group was able to form three-ringed structures completely encoding for cytosine using simple compounds. Their starting point, however, were relatively simple organic molecules, all of which may have come to exist in a prebiotic world. The breakthrough in the recent paper was the ability to generate those compounds out of simple hydrogen cyanide, using copper as a catalyst. Given that hydrogen cyanide has been found even in stars, a process describing life forming naturally using mainly hydrogen cyanide seems a more plausible explanation for abiogenesis. While there is much work to be done, this is a great leap forward for the field.

Understanding how life came to be is a question that has stirred our species since the dawn of philosophy and science. Having a reproducible, scientific model of this process is certainly a breakthrough for scientific reasons, but I would additionally argue that it is a boon for theology in that a seamless, functioning biological system derived purely from chemical and physical systems would be beautifully designed indeed. Regardless, there are many more mysteries to be unlocked, and I look forward to following the coming decades of progress.

Jack M. Cackler is a Ph.D. candidate in biostatistics. His column appears on alternate Wednesdays.