Question

The average distance between base pairs measured parallel to the axis of a DNA molecule is 3.4 Angstroms. The average molar mass of a pair of nucleotides is 650g/mol. Estimate the length in cm of a DNA molecule of molar mass 5.0 x 10⁹ g/mol. Roughly how many base pairs are contained in this molecule?

Answer 1

number of base pair = Molar mass of DNA molecule / mass of a base pair
                      = 5*10^9 g / 650 g
                      = 7.7*10^6

Total length of DNA molecule = number of base pair * distance between each pair
         = 7.7*10^6 * 3.4 Angstroms
         = 7.7*10^6 * 3.4 *10^-8 cm
         =0.26 cm