There are too many different combinations of amino acids and nucleic acids for a given enzyme or DNA sequence to come into existence by chance.
I. No one says they came into existence in one shot
This is true, but irrelevant to origin-of-life research, since no origin-of-life researcher supposes that modern enzymes and DNA strands came into existence all at once by pure chance. As Iris Fry explains, "origin-of-life theories rely on various organizing principles, including selection mechanisms and catalysis, that are supposed to have limited and constrained the wide scope of prebiotic chemical possibilities, thus constructing the scaffolding out of which the living arch eventually emerged" (Fry 2000:196).
II. Exact sequence not needed
It is also worth pointing out, of course, that enzymes with many different configurations can have identical or similar effects, meaning that no one particular enzyme must necessarily be generated in order to carry out a specific function.
Fry I. 2000. The Emergence of Life on Earth: A Historical and Scientific Overview. New Brunswick: Rutgers University Press.
Last update: 12 Jan 2015
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