The nitrogen-containing base is also known as nucleobase in the nucleotide molecule. It is in the form of a nitrogen-containing ring structure, known as a "base." This base is attached to the first carbon atom of the pentose sugar in the nucleotide molecule.
The sugar molecule in the nucleotide is a five-carbon molecule containing five carbon atoms; this sugar is known as pentose sugar. These sugars can be deoxyribose or ribose. Deoxyribose sugars form nucleotides serving as the monomers of deoxyribonucleic acids, or DNA, and ribose sugars form nucleotides serving as the monomers for ribonucleic acids, or RNA.
A nucleotide molecule contains phosphate groups attached to the fifth carbon atom of the pentose sugar. The phosphate groups can be one, two or three in number. DNA and RNA have triphosphate groups., i.e., three groups of phosphates. A DNA molecule can have dATP, dGTP, dCTP and dTTP groups, and a RNA molecule may have ATP, GTP, CTP and UTP groups.
DNA and RNA are macro molecules consisting of monomers of nucleotides as the basic building blocks. The nucleotide units are joined to each other by the third carbon atom of the pentose sugar. Also, the phosphate group in the nucleotide is attached to the fifth carbon of the adjacent pentose sugar forming the polymeric DNA or RNA structure.