Question

Linking number is associated with?

Answer 1

Linking Number:

1. In a covalently closed DNA molecule, the sum of these two parameters, known as the linking number (Lk = Tw + Wr), defines the topological properties of DNA, which are defined by twist (Tw, the number of times each helix twists around the other) and writhe (Wr, the number of crossings the double helix makes around itself).
2. The twist and writhe of any given DNA molecule must sum to the linking number.
3. Lk = Tw + Wr, so any change in the twist of the DNA will result in an equal and opposite change in the writhe (if the linking number is fixed), and any change in the linking number results in a change in the twist and/or writhe (∆Lk = ∆Tw + ∆Wr).