This attaches methyl groups (a carbon atom and three hydrogens) to either adenine or cytosine, two of the four chemical bases that form the alphabet of DNA, depending on the gene involved.

腺嘌呤和胞嘧啶是DNA四大成分其中之二，而到底附着于哪一个则取决于具体的基因。

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The genetic information of all living cells is stored in the DNA composed of the four canonical bases adenine (a), cytosine (c), guanine (g) and thymine (t).

所有活细胞的基因信息都储存在由四种碱基，即腺嘌呤(A)、鸟嘌呤(G)、胞嘧啶(C)、胸腺嘧啶(T)构成的DNA里。

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Adenine refers to a portion of the molecule, the nitrogenous base.

腺嘌呤指分子的一部分，即含氮碱基。

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The four bases - adenine (A), guanine (G), thymine (T), and cytosine (C) - spell out the genes.

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This seems to be because sirtuins control the abundance of a regulatory molecule called nicotinamide adenine diphosphate which, in turn, controls the release of energy in the mitochondria.

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Most important, they can't read the 3 billion letters--A, C, T and G, for the nucleotides adenine, cytosine, thymine and guanine--in the human genome from beginning to end, the way one reads a book.

FORBES: Magazine Article