The other chain is facing in the other direction, the 3' carbon is up, the 5' carbon is down.

对面的那条单链方向相反,3'位的碳原子向上,5'位的碳原子向下

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This blue chain here goes from 5' carbon all along the chain and there's a 3' carbon left open at the bottom.

这条蓝色的链,从5'碳开始一直向下延伸,以3'碳做为链的末端

耶鲁公开课 - 生物医学工程探索课程节选