Life with Metabolism VS Replication

It is logically possible to postulate organisms composed of pure hardware, capable of metabolism but incapable of replication. It is possible to postulate organisms composed of pure software, capable of replication but incapable of metabolism. And if the functions of life are separated in this fashion, it is to be expected that the latter type of organism will become an obligatory parasite upon the former. This logical analysis of the functions of life helps to explain and to correct the bias toward replication which is evident in Schroedinger's thinking and in the whole history of molecular biology. Organisms specializing in replication tend to be parasites, and molecular biologists prefer parasites for experimental study because parasites are structurally simpler than their hosts and better suited to quantitative manipulation. In the balance of nature there must be an opposite bias. Hosts must exist before there can be parasites. The survival of hosts is a precondition for the survival of parasites. Somebody must eat and grow to provide a home for those who only replicate. In the living world, as in the world of human society and economics, we cannot all be parasites.

When we begin to think about life's origins we meet again the question which Schroedinger did not ask, Is life one thing or two? And we meet again Von Neumann's answer, that life {64} is two things, metabolism and replication, and that the two things are logically separable. There are accordingly two logical possibilities for life's origins. Either life began only once, with the functions of replication and metabolism already present in rudimentary form and linked together from the beginning. Or life began twice, with two separate kinds of creatures, one kind capable of metabolism without exact replication, the other kind capable of replication without metabolism. If life began twice, the first beginning must have been with proteins, the second beginning with nucleic acids. The first protein creatures might have existed independently for a long time, eating and growing and gradually evolving a more and more efficient metabolic apparatus. The nucleic acid creatures must have been obligatory parasites from the start, preying upon the protein creatures and using the products of protein metabolism to achieve their own replication.


Folksonomies: evolution replication life definitions semantics metabolism

/food and drink (0.498714)
/society (0.485022)
/science/biology/molecular biology (0.433007)

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Schroedinger:City (0.959288 (positive:0.639557)), Von Neumann:Person (0.600943 (neutral:0.000000)), molecular biology:FieldTerminology (0.592798 (positive:0.639557))

DNA (0.981226): website | dbpedia | freebase | yago
Metabolism (0.915739): dbpedia | freebase
Virus (0.780976): dbpedia | freebase | opencyc
Biology (0.737209): dbpedia | freebase | opencyc
Protein (0.734094): dbpedia | freebase | opencyc
Biochemistry (0.731603): dbpedia | freebase | opencyc
Evolution (0.683020): dbpedia | freebase | opencyc
Gene (0.669302): dbpedia | freebase

 Infinite in All Directions
Books, Brochures, and Chapters>Book:  Dyson , Freeman J. (2004-07-22), Infinite in All Directions, Harper Perennial, Retrieved on 2012-04-25
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  • Folksonomies: religion