![A) Alanine synthesis using a Strecker mechanism, where the wiggly bonds indicate indeterminate stereochemistry. (B) Illustrating a calcium-promoted step on the reaction pathway where a PNC effect from Ca2+ could influence chiral preference at the Cα carbon (highlighted by circling in dashed blue). (C) An example of an Ala-bound calcium complex in a metal-mediated autocatalytic pathway, where L and L′ could be water, a bifurcating carboxylate from another amino acid [5], or other ligands. -- Life](https://i0.wp.com/astrobiology.com/wp-content/uploads/2024/01/Influence-of-the.png?resize=1200%2C900&ssl=1)
Natural chiral amino acids typically adopt an L structural configuration. While a preference for specific molecular chiralities is observed throughout biology and cellular chemistry, the origins of this preference are […]
Organic compounds, such as amino acids, are essential for the origin of life, and they may have been delivered to the prebiotic Earth from extra-terrestrial sources, such as carbonaceous chondrites.
We provide new support for habitable microenvironments in the near-subsurface of Mars, hosted in Fe- and Mg-rich rock units, and present a list of minerals that can serve as indicators […]
Isotopologue ratios are anticipated to be one of the most promising signs of life that can be observed remotely. On Earth, carbon isotopes have been used for decades as evidence […]
We present a simple mathematical model that captures the evolutionary capabilities of a prebiotic compartment or protocell.
![The effects of a four-day RPM exposure on the human squamous non-small-cell lung cancer cell line CRL-5889 according to Dietz and co-workers [196] (A–D). (A) The RPM exposure leads to partial detachment of cells from the bottom of the flask and after 24 h to first aggregations (spheroid formation) that further increase after 96 h. (D, black arrow). However, one part of the cells remains attached to the bottom of the bottle (D, adherent cells (AD), white arrow). These AD cells exhibit an upregulation of the PTEN, RB1, TP53, CDKN2A, and SOX2 gene expression, whose protein-to-protein interactions were shown by STRING analysis (B). In contrast under 1g on 2D cell culture plate the cells stay in a state of near confluence (C). These results are published in [196]. -- Life](https://i0.wp.com/astrobiology.com/wp-content/uploads/2023/12/CurrentKnowledgeabout.png?resize=1200%2C720&ssl=1)
Microgravity (µg) has a massive impact on the health of space explorers. Microgravity changes the proliferation, differentiation, and growth of cells.
Miller and Urey applied electric sparks to a reducive mixture of CH4, NH3, and water to obtain a complex organic mixture including biomolecules.
![Type II tRNA evolved via RNA ligation and a 9 nt internal deletion within ligated 3′- and 5′-acceptor stems [42]. Also, 3 31 nt minihelices (one D loop minihelix (magenta 17 nt core) and two anticodon stem-loop-stem minihelices (blue 17 nt core)) were fused by ligation for minihelix replication. The 93 nt tRNA precursor was processed by an internal 9 nt deletion (see below) within fused 3′-acceptor (yellow) and 5′-acceptor (green) stems. In the type II tRNA structure, the red arrow indicates the fusion of the magenta segment (17 nt D loop minihelix core; UAGCC repeat) and the green segment (5′-acceptor stem fragment; initially GGCGG). Abbreviations: SLS) stem-loop-stem; Ac) anticodon. Molecular graphics were created using ChimeraX [43]. -- Life](https://i0.wp.com/astrobiology.com/wp-content/uploads/2023/11/The331NucleotideMinihelix.png?resize=1200%2C720&ssl=1)
There are no theorems (proven theories) in the biological sciences. We propose that the 3 31 nt minihelix tRNA evolution theorem be universally accepted as one.
Reduced-oxidation-state phosphorus (reduced P, hereafter) compounds were likely available on the early Earth via meteorites or through various geologic processes.
Most contemporary theories for the chemical origins of life include the prebiotic synthesis of informational polymers, including strong interpretations of the RNA World hypothesis.
