The DNA (Deoxyribonucleic acid) is a double stranded structure. The two strands of the DNA are held together with the help of the hydrogen bonds. These hydrogen bonds exists between the nucleotides (A, T, C, and G). The bond between A and T is a double hydrogen bond, while that between C and G is triple bond. These hydrogen bonds between the nucleotides must be broken in order to unzip the DNA and continue with replication.