AP BIOLOGY

Detailed explanation-1: -Under normal circumstances, the nitrogen-containing bases adenine (A) and thymine (T) pair together, and cytosine (C) and guanine (G) pair together. The binding of these base pairs forms the structure of DNA.

Detailed explanation-2: -There are four nucleotides, or bases, in DNA: adenine (A), cytosine (C), guanine (G), and thymine (T). These bases form specific pairs (A with T, and G with C).

Detailed explanation-3: -In base pairing, adenine always pairs with thymine, and guanine always pairs with cytosine. Source: definition from the National Human Genome Research Institute (NHGRI) Glossary of Genetic Terms. In addition to the letters A, C, T, and G, a number of other abbreviations can be used to represent the nucleotide bases.

Detailed explanation-4: -Hence, guanine pairs with cytosine by formation of three hydrogen bonds.

Detailed explanation-5: -The four bases that make up this code are adenine (A), thymine (T), guanine (G) and cytosine (C). Bases pair off together in a double helix structure, these pairs being A and T, and C and G. RNA doesn’t contain thymine bases, replacing them with uracil bases (U), which pair to adenine1.