1·Adenine and guanine are purines and cytosine and thymine are pyrimidines.
腺嘌呤和鸟嘌呤是嘌呤和胞嘧啶和胸腺嘧啶是嘧啶。
2·The most abundant bases are cytosine, thiamine , and uracil ( pyrimidines ) and adenine and guanine ( purines ) .
最丰富的碱基是胞嘧啶， 胸腺嘧啶， 尿嘧啶，腺嘌呤和鸟嘌呤。
3·The other two, thymine and cytosine, are single ring structures called pyrimidines.
另两个为胸腺嘧啶和胞嘧啶，即称为嘧啶的单环结构。
4·Purines and pyrimidines have widespread and specific action in many tissues of both invertebrates and vertebrates.
在脊椎类和无脊椎类动物的多种组织中，嘧啶与嘌呤类物质具有广泛的特异性作用。
5·The most abundant bases are cytosine, thiamine, and uracil (pyrimidines) and adenine and guanine (purines).
最丰富的碱基是胞嘧啶，胸腺嘧啶，尿嘧啶，腺嘌呤和鸟嘌呤。