Question

12. Which type of chemical bond maintains the pairing of each chain in the DNA molecule?

Answer 1

To form the DNA molecule, purine bases bind to pyrimidine bases by intermolecular bonds called hydrogen bonds. Hydrogen bonds occur when there is hydrogen near one of these electronegative elements: fluorine, oxygen or nitrogen.

In such conditions hydrogen looks like having lost electrons for those elements and a very strong polarization is created. The highly positive hydrogen attracts pairs of electrons of other molecules making a hydrogen bond.