Self-replicated molecule

Even if It could be shown that RNA preceded both DNA and proteins in the march toward living things that doesn t automatically make RNA the first self replicating molecule Another possibility is that a self replicating polynucleotide based on some carbo hydrate other than o ribose was a precursor to RNA Over many generations natural selection could have led to the replacement of the other carbohydrate by D ribose giving RNA Recent research on unnatural polynucleotides by Professor Albert Eschenmoser of the Swiss Federal Institute of Technology (Zurich) has shown for example that nucleic acids based on L threose possess many of the properties of RNA and DNA... 

RNA replication have profound implications for investigations into the nature of self-replicating molecules that may have existed in prebiotic times. 

Molecular parasites may also have originated in an RNA world. With the appearance of the first inefficient self-replicators, transposition could have been a potentially important alternative to replication as a strategy for successful reproduction and survival. Early parasitic RNAs would simply hop into a self-replicating molecule via catalyzed transesterification, then passively undergo replication. Natural selection would have driven transposition to become site-specific, targeting sequences that did not interfere with the catalytic activities of the... 

Between 3 and 4 billion years ago the first self-replicating molecules appeared on earth. These entities had to have the capacity for extracting nutrients from the chemical compounds that existed in prebiotic times. We have some general notions about what types of substances were present at that time. One of the most important substances that was not present at that time in significant amounts was molecular oxygen, 02. Currently this form of oxygen is required by all forms of life visible to the naked eye. 

However, before bacteria could evolve, the fundamental chemistry of life needed to be established. For this we need to turn back the clock to around 4.5 - 4.1 billion years ago where the earth s crust has cooled and solidified and the oceans and atmosphere begin to form. It is speculated that iron-sulfide synthesis along deep oceanic platelets may have lead to the synthesis of the first RNA and self-replicating molecules. Exactly how this chemical evolution came about remains an open question. It is possible that RNA may have used clays and similar self-replicating materials as substrates. Eventually, this... 

Rebek s second generation of self-replicating molecules [59] which restrain the preassociative bimolecular pathway is a diaminocarbazole-based diimide, a nearly ideal complement to the purine nucleus of adenine. Conformational complications from the switching bound adenine between Watson-Crick and Hoogsteen binding modes are eliminated. 

The chiral RNA isomer pyranosyl-RNA (p-RNA, Scheme 14D), which has its ribose in the pyranosyl rather than in the furanosyl form, and phosphodiester linkages between the 2 and 4 positions, instead of 3 and 5, forms stronger and more selective hydrogen bonds than RNA. Moreover, it has recently been shown that p-RNA oligomerization on a p-RNA template is chiroselective for the formation of oligomers of the same handedness, which makes p-RNA a serious candidate to be considered as a possible precursor of RNA as the first self-replicating molecule. 

DNA. The fundamental requirement of a self-replicating molecule is that it can be synthesized from two or more components for which the molecule itself is the template. It is also vital that the dimer that forms upon completion of any bond formation during the template-assisted synthesis dissociates readily so that more components can bind to the original template and its newly created twin. Lastly, there must be an available pool of components. 

The design of self-replicating molecules, M. M. Conn and J. Rebek, Jr., Curr. Opin. Struct. Biol., 1994, 4, 629. 

Self replicating molecules that inherit genetic information... 

Such models can be developed for the computational design of catalytic sterns that self organize and adapt themselves for optimum catalytic performance. Adaptation occurs in the reproduction process with mutation of the self-replicating molecules coupled to the metabolic system. The metabolic system acts as the bio-immune molecular recognition and response system. The conditions for the emergence of such a stem are far from equilibrium in the complex regime. The behavior as a function of time is unpredictable, similar to the class 4 system proposed by Wolfram. 

Encoding self-replicating molecule. Proto-DNA or proto-RNA... 

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