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。

youdao

He USES zeroes and ones to represent the very first chemical building blocks of life (most likely compounds based on adenine, thymine, guanine, cytosine or uracil).

他用许多0和1来表示最早期时生命的化学成分(很可能是由腺嘌呤、胸腺嘧啶、鸟嘌呤、胞嘧啶和尿嘧啶组成的化合物)。

youdao

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。

youdao

These symbols represent the four basic chemical letters, or bases, the body uses to form DNA--guanine, cytosine, adenine and thymine.

FORBES: Magazine Article

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

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

BBC: DNA pioneer is honoured