DNA or Deoxyribonucleic acid is a polymer structured like a double helix consisting of two intertwined strands. Each strand consists of nucleotide bases linked to one another with strong covalent bonds. A base in one strand is linked to its opposite base in the other strand with weaker hydrogen bonds. Two such pairings are possible:
Adenine with Thymine and
Cytosine with Guanine.
