That's due to the asymmetry of the nucleotide, that there's a 5' and a 3' end and the way that they're linked together.

这是由于核苷酸的非对称性造成的,这里是5'端和3'端,这就是它们连接在一起的方式

耶鲁公开课 - 生物医学工程探索课程节选

This represents the upright struts on a ladder that I showed you before, it represents this backbone that's shown by - that's formed by polymerizing the pentose's together through phosphate's always going 5' to 3', 5' to 3'.

线条代表梯子,上下的支柱 之前给你们演示过,代表由多聚戊糖分子,通过磷酸基从5'端向3'端方向,连接起来的主链

耶鲁公开课 - 生物医学工程探索课程节选