Confounded cytosine! Tinkering and the evolution of DNA.
Early in the history of DNA, thymine replaced uracil, thus solving a short-term problem for storing genetic information--mutation of cytosine to uracil through deamination. Any engineer would have replaced cytosine, but evolution is a tinkerer not an engineer. By keeping cytosine and replacing uracil the problem was never eliminated, returning once again with the advent of DNA methylation.
Poole
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Institute of Molecular BioSciences, PO Box 11222, Massey University, Palmerston North, New Zealand. a.m.poole@massey.ac.nz
Penny
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Sjöberg
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D003596:Cytosine / Q000378:metabolism*; D004247:DNA / Q000235:genetics*; D019143:Evolution, Molecular
D003596:Cytosine; D004247:DNA