Guanine A nitrogenous base found in DNA and RNA.Guanine has a pruine ring structure.
是存在于DNA与RNA中的一种含氮碱基,具有一个嘌呤环结构。
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Now steroids are any compound with a specific 4-carbon ring structure, so the term steroid actually includes some chemicals that can be used to treat fever and headaches and even sex hormones like estrogen and testosterone.