Answer the following questions:

what type of bond holds the backbone of dna together and keeps the nucleotide sequence intact?
what type of bonds holds the complementary base pairs together at the nitrogen bases?

The building blocks of DNA are called nucleotides which is composed of a five carbon- sugar group, phospahate bond and four bases of nitrogen groups. this makes the DNA intact. The hydrogen bonds holds the complementary base pairs together at the nitrogen bases. The nitrogen bases are uracil, guanine, thymine and adenine.