The nucleotides in a nucleic acid are named after their nitrogenous bases. There are 4 different nucleotides in DNA. The bases point inward into the center of the double helix and bond together. Identify the complementary base pairs.

Adenine and Thymine (Uracil) are complementary base pairs

Guanine and Cytosine are complementary base pairs.

Explanation:

The genetic material (DNA and RNA) in living organisms is a nucleic acid composed of nucleotide building blocks. The nucleotides are structurally composed of three components viz: pentose sugar (Ribose or Deoxyribose), Nitrogenous bases (Adenine, Guanine, Cytosine, Thymine and Uracil), and a phosphate group.

These nucleotide subunits that make up nucleic acids are named after the Nitrogenous base contained in their structure. Each nucleotide is held to another by an hydrogen bond, which forms the double-helical structure of the DNA. However, according to Chargaff, a nuceleotide is bonded to another in the DNA using the complementary base pairing rule. The complementary base pairing rule states that Adenine (A) will always hydrogen bond to Thymine (T) while Guanine (G) will always hydrogen bond to Cytosine (C) i.e. A-T, G-C.