Charge transfer along a DNA molecule
Figure 2. (a) Charge carriers hop along the length of the DNA molecule from one GC base pair (black and orange) to the next.
(b) The relative energies of GC and AT base pairs in this DNA sequence show that a positively charged hole has a lower energy on the GC sites and moves from one GC pair to the next by coherent tunnelling through the AT sites. The overall motion from the first base pair to the last is an incoherent hopping mechanism in which the charged carrier is localized along the path. The total time it takes to move along the path is the sum of the times it takes to jump between individual GC base pairs, t12 + t23 +...+ t45. The process of charge-carrier hopping in DNA is analogous to crossing a river by jumping from one stepping stone to the next.