  Protons in the gap between base pairs of the double helix store the code of
life by breaking the chiral symmetry that swaps the sense strand with its
complementary partner. When these hydrogen bonds break during replication and
transcription, pairs of protons switch sides restoring chiral symmetry and
destroying genetic information. Using time-independent second-order
perturbation theory, we show that the observed rate of such spontaneous
mutations follows in the sudden approximation for bond breaking provided
protons in bonds between bases tunnel across the gap with terahertz
frequencies.
