base composition


base com·po·si·tion

the proportions of the four bases (adenine, cytosine, guanine, and thymine or uracil) present in DNA or RNA; usually expressed as the percentage (mol %) of G plus C.

base composition

The ratio of guanine + cytosine (GC) to adenine + thymine (AT) nucleotides in a nucleic acid; BC is usually expressed as a guanine + cytosine (G+C) value—e.g., 60% G+C. The GC content is of interest given that guanine and cytosine share three hydrogen bonds in double-stranded nucleic acids, compared to the two shared by adenine and thymine; the higher the GC content, the more stable the nucleic acid.