"It could be taken up by crustaceans like shrimp crabs, things like that which are the base of the food chain and that could be passed up to fish and then mammals and the toxins could be concentrated and that could be harmful to animals that feed on these smaller organisms."

VOA: standard.2010.05.09

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

耶鲁公开课 - 生物医学工程探索课程节选

They're colored different here to indicate one new difference that you know about now, and that's that there is an orientation, there's an up and down on the chain.

这里被涂成不同的颜色,来表示另一个不同之处,它是有方向的,表示双链一条向上,一条向下

耶鲁公开课 - 生物医学工程探索课程节选

The nucleotide has a directionality, there's an up and a down to it and it's going to turn out the chain that's formed by polymerizing these has a directionality as well and that's important in defining the structure.

核苷酸有方向性,有上端和下端,核苷酸长链,是由核苷酸沿一个特定方向聚合而成的,这在定义结构时很重要

耶鲁公开课 - 生物医学工程探索课程节选