The type of bond found between the nucleobases in a deoxyribonucleic acid, or DNA, molecule is a hydrogen bond. The four nitrogenous bases present in DNA include cytosine (C), guanine (G), adenine (A) and thymine (T).
DNA carries the genetic material of an organism. It is characterized by its double helix structure, where two strands twist around each other and run in opposite directions. DNA is a type of nucleic acid that is formed by repeating units called nucleotides, which serve as the molecule's building blocks. Each nucleotide comprises a deoxyribose sugar, a phosphate group and a nucleobase.
The four nucleobases found in DNA are classified into two categories: purines and pyrimidines. Purines are double-ringed and larger compared to pyrimidines, which only form single rings. A and G are purines, while C and T are pyrimidines. A purine always bonds with a pyrimidine.
The nitrogenous bases form complementary pairs. A only bonds with T and vice versa, while C only pairs with G and vice versa. The base pairs are located inside the double helix, arranged one on top of another, which is often likened to the rungs or steps of a twisted ladder. The A-T and T-A base pairs consist of two hydrogen bonds, while the C-G and G-C base pairs form three hydrogen bonds. This hydrogen-bonding mechanism is what gives DNA its characteristic shape.