Superhelical density

Superhelical density measures how tightly DNA is twisted or coiled beyond its normal relaxed state. Imagine a flexible string: when you twist it more than necessary, it becomes supercoiled. Similarly, in DNA, supercoiling affects how compact and accessible the genetic material is. Superhelical density quantifies this extra twisting; positive values indicate overwinding, while negative values indicate underwinding. This concept helps scientists understand DNA's structural state and its influence on processes like replication and gene expression.