Adenine will always bind with thymine and cytosine with guanine.

总是与胸嘧啶结合，嘧啶与鸟结合。

DNA is made of four organic bases: adenine, guanine, cytosine, and thymine, or A, G, C, and T.

DNA 由四种有机碱基组成：、鸟、嘧啶和胸嘧啶，即 A、G、C 和 T。

See, DNA is made up of four different building blocks called " bases" : adenine, cytosine, guanine, and thymine.

看，DNA 由四种称为“碱基”的不同构件组成：、嘧啶、鸟和胸嘧啶。

It was known that DNA had four chemical components - called adenine, guanine, cytosine, and thiamine - and that these paired up in particular ways.

当时已经知道，DNA含有4种化学成分——、鸟、嘧啶和胸嘧啶——这4种成分总是以特殊的配对方式排列。

The bases - the letters of the genetic alphabet - consist of the four nucleotides mentioned a page or two back: adenine, thiamine, guanine, and cytosine.

碱基——基因子母表中的字母——由前面我们提到的、鸟、嘧吟和胸嘧啶4种核苷酸组成。

Nucleotides of DNA are made out of a sugar deoxyribose, a phosphate, and one of the four nuclear bases: adenine, cytosine, guanine, and thymine or A, C, G, T for short.

DNA的核苷酸由脱氧核糖、磷酸以及四个核碱基之一组成，分别是、嘧啶、鸟与胸嘧啶，或简称A、C、G、T。

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.

该作用可以让甲基（由一个碳原子和三个氢原子组成）附着于或嘧啶上——组成DNA序列的四种主化学成分中的两种，到底附着的是哪种取决于涉及到的基因种类。

Nucleotides of DNA are made up of a sugar - deoxyribose, a phosphate, and one of the four nucleobases - adenine, cytosine, guanine, and thymine - or A, C, G, T for short.

DNA的核苷酸由一分子单糖-脱氧核糖、一分子磷酸与四种核碱基之一的（A）、嘧啶（C）、鸟（G）或胸嘧啶（T）组成。