Cytosine organic compound of the pyrimidine family often called a base consisting of a single ring containing both nitrogen and carbon atoms and an amino group.

胞嘧啶：嘧啶族的有机化合物。常被称为基，包含一个单环，内有氮原子和碳原子，还有氨群。

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Much is known about the "fifth base, " 5-methylcytosine, which arises when a chemical tag or methyl group is tacked onto a cytosine.

此前，科学家们已对第5种碱基有所了解——当一个化学标签或甲基被固定到一个胞嘧啶上时，第5种碱基就会出现。

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