Nitrogenous bases are the parts of RNA and DNA that are involved in pairing up (see also base pairs). These include cytosine, guanine, adenine, thymine (DNA) and uracil (RNA).
... wife of the bureaucrat Karenin. She is invited from her home in St Petersburg to Moscow to mediate the marital discord of her brother Stepan (Stiva) Oblonsky and his wife ...