What is Life?:How chemistry becomes biology by Addy Pross

merely preaches a more elaborate form of reduction, one that recognizes that causal relations within a system can be more complex than those implied by a simple bottom-up causal chain. To quote Athel Cornish-Bowden, the British biologist:
the classical reductionist approach to science can be understood as a way of understanding the functioning of a whole system in terms of the properties of its parts, but now we must learn to understand the parts in terms of the whole. 26
     
    Reduction as an explanatory tool in science is difficult to circumvent because reduction is a key means of obtaining scientific understanding. Despite several decades of groping expectantly toward some kind of non-reductionist or even anti-reductionist methodology, that activity does not seem as yet to have born edible fruit. Holism, despite its name, can be thought of as just a reductionist elaboration, a potentially valuable elaboration for sure, but an elaboration nonetheless. Reduction in its various forms and sub-forms, was, is, and will likely remain the central conceptual tool in scientific endeavour. To the extent that the ‘what is life’ question
can
be satisfactorily resolved, I believe it can only be through a fundamentally reductionist approach—by seeking the underlying connections between chemistry and biology, by identifying the process responsible for biological complexification. Ultimately the difference between animate and inanimate must be reduced to differences in the nature of the materials within the two worlds and, in particular, in the way those materials interact and react.

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Stability and Instability
     
Why do chemical reactions occur?
     
    All living things involve chemical reactions, thousands of them, and the living cell, the basic unit comprising all life, is a highly complex set of these reactions somehow integrated into a coordinated whole. This fact alone makes the problem of understanding the living state of matter and the elucidation of its underlying characteristics a difficult one. How can that complex interplay of reactions and the molecular entities on which they operate be unravelled? Are some reactions central while others are peripheral? Of course, if we are seeking a better understanding of the reactions of life, we first need to understand chemical reactions in general. What is a chemical reaction and why do they take place? So let us begin by making some general comments about chemical reactivity. The subject is complex, one that requires textbook coverage for a proper treatment. Here I will give a greatly simplified version that primarily addresses those aspects of reactivity that we will need for oursubsequent analysis. Our analysis will reveal that there
is
something very special within the set of chemical reactions that constitute life and understanding what that special feature is will be a focus of the ensuing chapters.
    All chemical reactions involve the transformation of some chemical material into some other material. The neutralization of an acid by a base, the degradation of a protein into its constituent amino acid building blocks, the explosive reaction of a mixture of hydrogen and oxygen gases to give water, are all examples of common chemical reactions. This last reaction, that of hydrogen and oxygen gases, occurs very readily—a spark or the presence of a catalyst (for example, metallic platinum or palladium) is all that is needed for it to take place. The reverse reaction in which water spontaneously breaks up into hydrogen and oxygen gases does not occur. Why is that? What governs the direction of a chemical reaction? Broadly speaking, the answer is given by a central law of chemistry, one we have already met briefly—the Second Law of Thermodynamics.
    The Second Law is actually a fundamental law of physics, so its wide applicability means that it has a number of different formulations. But in the present context it will suffice to say that chemical reactions proceed such that
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