In a nucleic acid molecule, a nitrogenous base is linked to a sugar molecule through a _ bond.
The correct answer and explanation is:
In a nucleic acid molecule, a nitrogenous base is linked to a sugar molecule through a glycosidic bond.
A glycosidic bond is a covalent bond that forms between the nitrogenous base and the sugar molecule in nucleotides. In the context of nucleic acids such as DNA and RNA, this bond connects the nitrogenous base to the 1′ carbon atom of the sugar molecule, which is deoxyribose in DNA and ribose in RNA. The specific linkage occurs at the nitrogen atom of the purine or pyrimidine base and the anomeric carbon of the sugar.
In the structure of nucleic acids, nucleotides are the building blocks, and each nucleotide consists of three components: a nitrogenous base, a five-carbon sugar, and a phosphate group. The nitrogenous base can be either a purine (adenine or guanine) or a pyrimidine (cytosine, thymine, or uracil). The sugar molecule is the backbone of the nucleic acid chain and provides stability to the structure.
In DNA, the sugar is deoxyribose, which lacks one oxygen atom compared to ribose, the sugar found in RNA. The nitrogenous base is attached to the sugar through the glycosidic bond at the 1′ carbon, while the phosphate group is linked to the 5′ carbon of the sugar. This bonding arrangement allows the formation of a long, stable polymer chain of nucleotides, which forms the backbone of DNA and RNA.
The glycosidic bond is crucial for the integrity of nucleic acid molecules. It helps maintain the specific sequence of bases, which is essential for the storage and transmission of genetic information. It also contributes to the structural stability of the nucleic acid and its ability to undergo processes such as replication and transcription.