1. A nitrogenous base: This is a ring-shaped molecule with nitrogen atoms. There are five main types of nitrogenous bases: adenine (A), guanine (G), cytosine (C), thymine (T), and uracil (U). Adenine and guanine are purines, while cytosine, thymine, and uracil are pyrimidines.

2. A five-carbon sugar (pentose): This is a sugar molecule with five carbon atoms. The sugar in DNA is deoxyribose, while the sugar in RNA is ribose.

3. A phosphate group: This is a molecule composed of phosphorus and oxygen atoms.

These three components are linked together in a specific way: the nitrogenous base is attached to the 1' carbon of the sugar, and the phosphate group is attached to the 5' carbon of the sugar.

Nucleotides are the building blocks of nucleic acids, such as DNA and RNA, which are essential for life.