helicoidal bottom

例句：

1. 1. The molecule has a helical structure that is characteristic of proteins.
   这种分子具有螺旋结构，这是蛋白质的典型特征。
2. 2. The spiral staircase leads to the top floor of the building.
   螺旋楼梯通向大楼的顶层。
3. 3.The DNA molecule is helical, with each nucleotide forming a turn in the helix.
   DNA分子是螺旋状的，每个核苷酸都在螺旋中形成一圈。