In a nucleotide, the nitrogenous base is attached to the 1′ carbon (also referred to as C1) of the sugar molecule. This sugar is typically ribose in RNA and deoxyribose in DNA.
The attachment occurs through a glycosidic bond, which forms when a nitrogen atom of the base interacts with the 1′ carbon of the sugar. This structure is crucial for the formation of nucleic acids, as it allows the nitrogenous base to extend outward, making it accessible for base pairing during processes like DNA replication and RNA transcription.