Theoretical origin of life; a computer model (Introduction)

by David Turell , Tuesday, July 28, 2015, 18:49 (3406 days ago) @ David Turell

Based on lots of hopeful sentiment about small peptides linking up. Computer models can suggest anything, and this is obviously a model built on chance connections of peptides. How can anything meaningful develop?:-http://www.sciencedaily.com/releases/2015/07/150728110720.htm-"Tkachenko and Maslov have proposed a new model that shows how the earliest self-replicating molecules could have worked. Their model switches between "day" phases, where individual polymers float freely, and "night" phases, where they join together to form longer chains via template-assisted ligation. The phases are driven by cyclic changes in environmental conditions, such as temperature, pH, or salinity, which throw the system out of equilibrium and induce the polymers to either come together or drift apart.-"According to their model, during the night cycles, multiple short polymers bond to longer polymer strands, which act as templates. These longer template strands hold the shorter polymers in close enough proximity to each other that they can ligate to form a longer strand -- a complementary copy of at least part of the template. Over time, the newly synthesized polymers come to dominate, giving rise to an autocatalytic and self-sustaining system of molecules large enough to potentially encode blueprints for life, the model predicts."-***-Under Tkachenko and Maslov's model, the move from monomers to polymers is a very sudden one. It's also hysteretic -- that is, it takes a very certain set of conditions to make the initial leap from monomers to self-replicating polymers, but those stringent requirements are not necessary to maintain a system of self-replicating polymers once one has leapt over the first hurdle.-One limitation of the model that the researchers plan to address in future studies is its assumption that all polymer sequences are equally likely to occur. Transmission of information requires heritable variation in sequence frequencies -- certain combinations of bases code for particular proteins, which have different functions. The next step, then, is to consider a scenario in which some sequences become more common than others, allowing the system to transmit meaningful information-***-Summary: "Recent research by Tkachenko and Maslov, published July 28, 2015 in The Journal of Chemical Physics, suggests that self-replicating molecules such as RNA may have arisen through a process called template-assisted ligation. That is, under certain environmental conditions, small polymers could be driven to bond to longer complementary polymer template strands, holding the short strands in close enough proximity to each other that they could fuse into longer strands. Through cyclic changes in environmental conditions that induce complementary strands to come together and then fall apart repeatedly, a self-sustaining collection of hybridized, self-replicating polymers able to encode the blueprints for life could emerge."