DNA Biophysics
The physical study of mechanical stiffness, elasticity, topology, and base-pairing thermodynamics of double-stranded DNA.
Governing formula
Persistence Length A_p ≈ 50 nm, Contour Length L
SI unit
nm (Persistence Length) & pN (Stretching Force)
In depth
Double-stranded DNA acts as a semi-flexible polymer with a persistence length of ~50 nm (~150 base pairs). Topoisomerase enzymes manage supercoiling knotting during transcription and replication.
Examples in the real world
Optical tweezers pulling individual DNA strands to measure mechanical overstretching transitions at 65 pN force.