Abstract
In the mid-twentieth century, multiple Nobel Prizes rewarded discoveries of a seemingly universal set of molecules and interactions that collectively defined the chemical basis for life. Twenty-first-century science knows that every detail of this Central Dogma of Molecular Biology can vary through either biological evolution, human engineering (synthetic biology) or both. Clearly the material, molecular basis of replicating, evolving entities can be different. There is far less clarity yet for what constitutes this set of possibilities. One approach to better understand the limits and scope of moving beyond life's central dogma comes from those who study life's origins. RNA, proteins and the genetic code that binds them each look like products of natural selection. This raises the question of what step(s) preceded these particular components? Answers here will clarify whether any discrete point in time or biochemical evolution will objectively merit the label of life's origin, or whether life unfolds seamlessly from the non-living universe.
Highlights
Fifty years later, the situation has changed
Of change over time time self-organizing matter chemical evolution evolution by natural selection molecular evolution as we know it Origin of ? life more numerous and diverse alternatives to nucleobases [16,17], amino acids [18,19,20] and genetic codes [21]
But arguably deeper implications arise for understanding abiogenesis when such flexibility is considered in the light of further studies which show collectively that each component of the central dogma resembles an outcome of natural selection
Summary
Three publications described how the genetic material of more than 200 bacteriophage viruses uses 1-aminoadenine (Z) instead of adenine (A) [1,2,3,4] This minor difference in chemical structures is a fundamental deviation from the standard alphabet of four nucleobases established by biological evolution at the time of life’s Last Universal Common Ancestor (LUCA). Each protein sequence is specified by a corresponding gene sequence [8] through a genetic code that defines a meaning (translation) for every possible genetic code-word [9] These foundations of biochemistry became known as the Central Dogma of Molecular Biology [10] and more than one of the Nobelwinning scientists talked about having uncovered the ‘secret(s) of life’ [11,12].
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