Amino acids from the late Precambrian Thule group, Greenland

Silica-Carbonate of Ba(II) and Fe2+/Fe3+ Complex as Study Models to Understand Prebiotic Chemistry

The Precambrian era is called the first stage of the Earth history and is considered the longest stage in the geological time scale. Despite its duration, several of its environmental and chemical characteristics are still being studied. It is an era of special relevance not only for its duration but also because it is when a set of conditions gave rise to the first organism. This pioneer organism has been proposed to have been formed by a mineral and an organic part. A chemical element suggested to have been part of the structure of this cell is iron. However, what special characteristic does iron have with respect to other chemical elements to be proposed as part of this first cell? To answer this and other questions, it is indispensable to have a model that will allow extrapolating the first chemical structures of the pioneer organism formed in the Precambrian. In this context, for several decades, in vitro structures chemically formed by silica-carbonates have been synthetized, called biomorphs, because they could emulate living organisms and might resemble primitive organisms. It has been inferred that because biomorphs form structures with characteristic morphologies, they could resemble the microfossils found in the cherts of the Precambrian. Aiming at providing some insight on how iron contributed to the formation of the chemical structures of the primitive organism, we evaluated how iron contributes to the morphology and chemical-crystalline structure during the synthesis of these compounds under different conditions found in the primitive atmosphere. Experimentally, synthesis of biomorphs was performed at four different atmospheric conditions including UV light, nonionizing microwave radiation (NIR-mw), water steam (WS), and CO2 in the presence of Fe2+, Fe3+, and Fe2+/Fe3+, obtaining 48 different conditions. The produced biomorphs were observed under scanning electron microscopy (SEM). Afterward, their chemical composition and crystalline structure were analyzed through Raman and IR spectroscopy.

Could organic matter have been preserved on Mars for 3.5 billion years?

3.5 billion years (byr) ago, when it is thought that Mars and Earth had similar climates, biological evolution on Earth had made considerable progress, such that life was abundant. It is therefore surmised that prior to this time period the advent of chemical evolution and subsequent origin of life occurred on Earth and may have occurred on Mars. Analysis for organic compounds in the soil buried beneath the Martian surface may yield useful information regarding the occurrence of chemical evolution and possibly biological evolution. Calculations based on the stability of amino acids lead to the conclusion that remnants of these compounds, if they existed on Mars 3.5 byr ago, might have been preserved buried beneath the surface oxidizing layer. For example, if phenylalanine, an amino acid of average stability, existed on Mars 3.5 byr ago, then 1.6% would remain buried today, or 25 pg-2.5 ng of C g-1 Martian soil may exist from remnants of meteoritic and cometary bombardment, assuming that 1% of the organics survived impact.