本文研究了2700 bp DNA片段在金属离子作用下,折叠缩合为复曲面的形成过程。以电子显微镜术为手段,经大量观测抽提出几种典型中间结构,并计算了各典型结构的尺度分布。作者由此推论,DNA缩合结构的形成过程是DNA链折叠与排列的过程;是无序到有序的转化过程。研究不仅证实缩合是有规则与有方向的,还进一步证实短DNA片段的缩合是多分子的缩合。 In this paper, we investigated the formation of a toric surface by folding and condensing a 2700 bp DNA fragment under the action of metal ions. With electron microscopy as a means, several typical intermediate structures were extracted after extensive observation, and the scale distribution of each typical structure was calculated. From this, the author deduces that the formation of DNA condensation structure is the process of folding and arranging DNA strands; the process of transformation from disorder to order. The study not only confirmed that the condensation is regular and directional, but further confirmed that the condensation of short DNA fragments is multimolecular condensation.