To calculate the charge contained in 1 nm (1 nanometer) of DNA, we need to consider the structure and composition of DNA.

DNA (deoxyribonucleic acid) is a polymer made up of nucleotides, which consist of a phosphate group, a deoxyribose sugar, and a nitrogenous base. The phosphate groups carry a negative charge, while the deoxyribose and nitrogenous bases are uncharged.

In a DNA double helix, the two strands are held together by hydrogen bonds between the complementary base pairs (adenine-thymine and guanine-cytosine). Each nucleotide in the DNA strand has one phosphate group, and the distance between adjacent phosphate groups (also known as the phosphate-phosphate distance or the rise per base pair) is approximately 0.34 nm.

To calculate the charge contained in 1 nm of DNA, we need to determine the number of phosphate groups present in that length.

Given:

• Charge of one phosphate group = -1 elementary charge (e)
• Rise per base pair (phosphate-phosphate distance) = 0.34 nm

Number of phosphate groups in 1 nm = 1 nm / 0.34 nm ≈ 2.94 phosphate groups

Therefore, the charge contained in 1 nm of DNA is approximately:

Charge = 2.94 × (-1e) = -2.94e

Where “e” is the elementary charge (the charge of a single electron or proton), which is approximately 1.602 × 10^-19 coulombs.