In this case, this particular restriction enzyme cuts symmetrically like this, but not at the same point.

在我们这种情况下,这个限制性内切酶总是这样对称地切割,但两条链切割的位点不一样

耶鲁公开课 - 生物医学工程探索课程节选

That there are two colors per strut, so what's linking the two backbones together are two colored segments that come from the outside towards the middle, and that the colors occur only in certain combinations, red and green, yellow and blue, that's all you see.

每个梯阶有两个颜色,主链是由,两种不同颜色的片段由外向内连接起来的,这些颜色仅以某种特定方式配对,红连接绿,黄连接蓝,大家都能看到

耶鲁公开课 - 生物医学工程探索课程节选