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Sto caricando le informazioni... What is life? : how chemistry becomes biology (originale 2012; edizione 2012)di Addy Pross
Informazioni sull'operaWhat is Life?: How Chemistry Becomes Biology di Addy Pross (2012)
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Iscriviti per consentire a LibraryThing di scoprire se ti piacerà questo libro. Attualmente non vi sono conversazioni su questo libro. Interesting book. Here is my review. ( ) We lack an adequate theory of what life is, and therefore cannot give adequate answers to fundamental questions in biology. What are the principles at work in abiogenesis, the emergence of life from inanimate chemical building blocks? What principles guide life’s arrant defiance of the Second Law of Thermodynamics, the demand that systems tend toward maximum disorder? How is it that life, which behaves as if it has purpose could come about from a universe without purpose? I was prepared to report that this book was dry, pessimistic, and set up the reader for a lackluster attempted salvation by our heroic author/scientist. So the unexpected urgency that overcame me upon completion took me by surprise. After I finished the book, I realized I wasn’t finished at all. I needed to review to make sure I understood these proposals, research the status of Pross’ ideas in biology, and write it all out for the sake of clarity. A complete summary of these ideas is beyond the scope of this review. I will focus on the core concept, one with which I had not previously been familiar. He argues that despite efforts to identify the historical origin of life on Earth some 4 billion years ago -- ocean thermal vents, the clay template model, primitive redox reactions across proto-membranes – it is likely we will never have conclusive answers about these matters. The more knowable – and more important – question surrounds the principles at work in the establishment of life and in propelling it from the simple to complexity. A fundamental characteristic of life from a chemical point of view is its organization, its movement from the simple to the complex. Life persists despite by its very nature opposing the principle that guides all physical systems: the thermodynamic tendency to move toward maximum disorder, toward a state of maximum stability, toward the endpoint of reactivity. The explanation has always made sense. Systems can resist this thermodynamic imperative as long as they have an input of energy that powers the opposing tendency toward disorder. What Pross has done is to detail how life gets around the Second Law without violating it, and in so doing he elaborates explanatory chemical principles that illuminate the nature of life. The proposal here is a fundamental chemical principle that allows life to perpetuate itself despite the inexorable requirement of the Second Law. His idea comes out of the field of chemical systems, specifically replicating systems. Replication is fundamental to life. Life makes more copies of itself. The genetic code is copied and recopied billions of times per day. Every protein in every cell is replaced in a perpetual process of making more and more of the chemicals of life. The better at replicating, the more persistent life is over time. Replicating systems are stable, in the sense of persisting, not by reaching an endpoint of reactivity as in classical chemical reactions. Instead, replicating systems are stable when they are powerfully able to sustain the activity of replication by ready access to the reactant materials used in the replication process. In this way, living systems have a different kind of stability than do conventional chemical reactions, which can be called dynamic kinetic stability. A waterfall supplies a visual example. It is a system that persists by the constant turnover of its materials (water) and the ongoing energy supply that comes from the conversion of potential to kinetic energy. Like the waterfall, life is driven by the stability that comes from the nature of replicative chemistry. For the author, a division between chemistry and biology is misleading. Biological systems are a form of organized and “complexifying” replicative chemical systems. Pross concludes with his own definition: life is a “self-sustaining kinetically stable dynamic reaction network derived from the replication reaction”. It’s a beautiful addition to our understanding of what is fundamental about life. The book was valuable to me. I recommend it highly if the topic is of interest. If this brief review doesn’t intrigue you, I’d suggest something else. After spending the first few chapters outlining the major obstacles to developing a theory of abiogenesis, Pross then proceeds to lay out his proposed solution to the problem. I found his analysis of the intractable problems of abiogenesis to be insightful and spot on with what I know from my other reading in origin of life research. Then in the second half of the book he, almost too glibly, in my opinion, outlines his solution to the problem, which in a nutshell, is that life evolved from chemical networks of self-replicating systems. In order to make his theory even possibly plausible, he makes the assumption that life , for certain, arose from non-life by natural processes. He then proceeds to outline what he sees as the driving force of abiogenesis, dynamic kinetic stability (DKS). Like all theories of abiogenesis, this one also suffers from the same inherent problem, the needed ingredients to even get a system like he describes started is beyond statistical possibility. The only way Pross manages to maintain confidence in his theory, is the assumption that life DID arise by natural processes, thus his theory is the most likely way it happened. Chemistry lives! -- a 200-page argument that "systems chemistry", concerned with "dynamic kinetic stability" of collections of molecules, is the science that will explain prebiotic evolution (by "kinetic selection") and the origin of life. "[Life is] _a self-sustaining kinetically stable dynamic reaction network derived from the replication reaction_." (p 164, emphasis in original.) Pross at once shuns "teleology" and embraces "teleonomy", and that's one of the things that made me think that some of the ideas in Terrence Deacon's formidably profound _Incomplete Nature_ should be added to the mix too. nessuna recensione | aggiungi una recensione
Appartiene alle Collane Editoriali
Seventy years ago, Erwin Schro dinger posed a simple, yet profound, question: 'What is life?'. How could the very existence of such extraordinary chemical systems be understood? This problem has puzzled biologists and physical scientists both before, and ever since.Living things are hugely complex and have unique properties, such as self-maintenance and apparently purposeful behaviour which we do not see in inert matter. So how does chemistry give rise to biology? Did life begin with replicating molecules, and, if so, what could have led the first replicating molecules up such a path? Now, deve Non sono state trovate descrizioni di biblioteche |
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