A nucleotide, the fundamental unit of DNA and RNA, comprises three key components.
The building block of DNA and RNA, a nucleotide, is made up of three essential parts. First, a sugar molecule that forms a pentose sugar is either ribose in RNA or deoxyribose in DNA. Second, a phosphate group—which is made up of one phosphorus atom bound to four oxygen atoms—attaches itself to one side of the sugar.
Thirdly, a nitrogenous base attaches to the opposite side of the sugar. This base can be adenine (A), uracil (U), cytosine (C), and guanine (G) in RNA, or thymine (T), cytosine (C), and guanine (G) in DNA. The nucleic acid sequences are based on this structural arrangement.