Question

DNA segment in a neutral pH solution are negatively charged, there are two excess electrons per base pair if a 0.1 micron DNA fragment has a charge of $-9.1\times {10}^{-17}C$, how many basepairs are there along this fragment?

Answer 1

Electron charge $=-1.60217662\times {10}^{-19}Coulombs$
There are 2 electrons per base pair, and total charge of 0.1 microns of DNA is $-9.1\times {10}^{-17}Coulombs.$
$\frac{(-9.1\times {10}^{-17})}{(-1.60217662\times {10}^{-19})}=568$
As, 2 electrons make 1 base pair.
$\frac{568}{2}=284$ base pairs.