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

生物医学工程探索课程节选 : 耶鲁公开课