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.
Institute of Molecular BioSciences, PO Box 11222, Massey University, Palmerston North, New Zealand. a.m.poole@massey.ac.nz
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D003596:Cytosine / Q000378:metabolism*; D004247:DNA / Q000235:genetics*; D019143:Evolution, Molecular
D003596:Cytosine; D004247:DNA