It wouldn't be the same if I turned it upside down because the carbons - the rings here, the pentose's would all be turned over, the chemistry would look different and the sequence of bases would look different.

记住单链倒过来,就和原来不一样了,这是因为碳原子和糖环结构,戊糖会翻转,使得这个化学结构看起来不一样了,碱基的顺序也不一样了

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