n.螺旋结构
Coil the fibre into a helix.
将纤维卷绕成螺旋形。
Normal, double - helix DNA is spiral, like a loosely coiled spring.
正常的双螺旋DNA是螺旋形的, 像一根松松地卷曲的弹簧.
The helix makes a complete turn every 3.6 residues.
每个3.6个残基,螺旋正好转一圈.