Abiogenesis

Initial Words:I am sorry for this short reply.I kind fo forgot about this debate and haven't had much time to put thought into it, and am quite busy now. Preface: Abiogenesis is the study of how one can get from raw chemistry to life, which is a prediction made by a naturalistic origin of life (OOL) and must have occurec at least ~3,700 MYa, from our oldest stromatolites [1]. To clear up a misconception very quickly, abiogenesis is not spontaneous generation, a long discarded hypothesis for the OOL. Furthermore abiogenesis does not depict the formation of the universal common ancestor for life [2], although they are chronologically close in the concentional timeline for life.RNA World Hypothesis:The hypothesis I will be defending in this debate is the RNA World Hypothesis, there are other independantn hypothesis currently being investigated each with their own advantages, such as metabolism-first, lipid world and even more extravagent ones such as extraterrestial material etc. The RNA world hypothesis depicts a habitat with everyhting mediated by purely RNA based structures, and precedes the current protein/DNA driven biological systems we have today. There are reasons from our current biology today to assume off hand this is a plausible explanation. One is the make-up of the ribosome. Ribosomes are found in every single living thing today and are a critical component of these cells involved in tranlation of mRNA to form peptide chains. There are aproximately 60% rRNA by weight and functions very much like a ribozyme, furthermore other critical structures (which form parts the foundational systems of all current living cells) such as Acetyl-CoA, ATP, FAD & NAH+ are indeed largely RNA based [3].If evolution was thought of as a house that's being built, the most important features, such as the foundations, the frame and supporting columns would be the ones both build first and the most difficult to change once the house has been built on top of it. This is very much the same case in the RNA World Hypothesis.Abiotic formation of RNA:Note that the conditions of the early Earth predicted and found by conventional science are very different to what we observe today. First and foremost there was no oxygen in the environment, the Earth formed from the same material the sun was formed from, and therefore contained an enormous amount of hydrogen, which set the Earth in a largely reduced state [4]. Therefore the same problems that would occur today with regards to oxygen-driven drgradation of RNA molecules would not have been originally possible.Moreover, simple pyrimadine nucleotides have been synthesized under conditions thought to occur during the Early earth [5][6], these include the use of cyanamide, cyanoacetylene, glycolaldehyde, glyceraldehyde and inorganic phosphate, all very plausible simple early earth feedstock molecules (many are released geothermally). What is most striking is that careful controls are not needed to allow the reactions to procede, as the pH is controlled by the inorganic phosphate present (which isn't incorperated until late in the synthesis) and furthermore the synthesis bypasses the formation of the free ribose and nucleic base synthesis to form the nucleotides, which signfiicantly reduces the amount of 'luck' required to make these nucleotides. Formation of polynucleotides:Given that we have a synthesis of nucleotide monomers, oligomers and polymers are formed by the coupling of multiple monomers into a linear chain. These don't occur readily at room temperature, but is know that inorganic clay, which were likely present on the early Earth, are perfectly capable of the catalysis of the formation of these chains [7]. These chains will be largely random in the order the amino acids are in. What is interesting is that very long polymers and 'tarred' impurities, which is basically the 'gunk' you get if you heat a mixture of chemicals too hot and too long, these impurities naturally remain as a solid phase, and do not significantly pariticipate what occurs within the solution phase.Moreover these RNA strands can duplicate using nothing but heat, which was in abundance at the time due to the geology of the Earth at the time. This process is frequently in use today in the polymerase chain reaction, where many billions of copies of genses are produced rapidly via a cycled heating/cooling process.What's more is that these RNA strands can fold on itself to form three dimensional structures, similar to the structures we see in proteins. What the RNA worl hypothesis needs is just one of these randomly produced structures to show some ability to assist the replication of RNA (the role that was initially taken by the clays).Compartmentalisation:Will expand on this in next round, as I'm running out of time. These involve abiotic lipid membranes that naturally form and comparmentalize these replication systems. Allowing for a simple system of purification and drive for replication.Autocatalysis:Once we have a strand of RNA that assists the replication of other RNA molecules, the system becomes autocatalytic, and hence evolution takes over, and the role of abiogenesis is done. The first primitive RNA based life is formed.References:[1] http://www.paleosoc.org...;[2] http://en.wikipedia.org...;[3] http://en.wikipedia.org...(biochemistry) [4] [5] http://www.nature.com...[6] http://www.wired.com...[7] http://www.sciencedirect.com...;