Theoretical origin of life; 15 questions (Introduction)

by David Turell , Saturday, June 13, 2015, 15:40 (3451 days ago) @ David Turell

A list of the difficulties in theorizing how life began:-http://www.lifephys.dis.titech.ac.jp/oqol2014/?page_id=180-Below I've picked out a few of the questions. In total the article shows how little we really know from 60 years of research.-"All life is based on proteins and nucleic acids, which are ordered sequences of units. Not to be confused with a simple random polymerization or copolymerization. The question “how can we make by prebiotic means ordered sequences of amino acids, or mononucleotides?” is in fact never asked in the modern research on the origin of life.-"Premise: Why is the origin of life still a mystery? Yes, we all in science accept 1924 Oparin's idea that life on Earth originated from the inanimate matter via a series of chemical steps of increasing molecular complexity and functionality. However, the turning point nonlife-life has never been put into one experimental set up-actually it has never be clarified this from a conceptual point of view either. There are of course several hypotheses, and this plethora of ideas means already that we do not have a convincing one. -" At the early stage of RNA world, RNA molecules should have no functional property. What physical or chemical process mediates the selection of specific RNA? Even when functional RNA enzymes are generated, it still remains a challenge to construct sustained self-replication and metabolic system in which multiple RNA molecules function cooperatively. Once we can construct the precursor of a replication system by a set of RNA molecules, is it possible to emulate another path of evolution in a test tube?-"The genetic code is most essential part for the genetic systems. In the context of the origin of life, a major issue on the genetic code is to understand how the materials relevant to genetic code that can translate the sequence of four bases into a polypeptide. In bacteria and cells, each of ~20 different amino-acyl tRNA synthethase (aa-RS) bind to a particular tRNA with high affinity and also has an specific binding to one of twenty amino acids. The aa-RS produces amino-acyl tRNA (aa-tRNA) that has the triplet of anti-codon in a loop of tRNA and a corresponding amino acid at 3' end. How was a family of aa-tRNAs created without sophisticated enzymes? Although RNA-catalyzed self-aminoacylation and tRNA aminoacylation has been demonstrated experimentally, the possible evolutional pathway of genetic coding system is little understood. Can we find or design simple aa-RS and aa-tRNA from the cocktail of molecules (e.g., amino acid, tRNA(-like) molecule, and ATP), which might be relevant to the origin of translation and genetic code? What features are required as a mechanism that ensures robust translation? (my bold)-"The Premise: The transition from non-living to living systems involves, as a key step, the formation of a self-bounded physical system that contains interacting molecules. In many proposed scenarios, the complexity of such an event is often underestimated, and it is typically taken for granted, starting from the separated components. However, compared to the large amount of work done for understanding the emergence and the evolution of functional molecules and networks (ribozymes, catalytic peptides, simple metabolic cycles, self-replicating molecules, hypercycles and autocatalytic sets, etc.), much less has been done for understanding the physical mechanisms underlying the assembly of primitive cell-like structures. In particular, little attention has been given to go beyond the general and simplistic sentence ‘… and later became encapsulated in a membrane-based compartment'. (my bold)