The structure of a nucleotide, consisting of a phosphate group (left), a pentose sugar molecule (middle), and a nitrogenous base (right). (Image: Public Domain) Ribonucleotides are the building blocks ...

Nucleotides themselves are composed of three distinct parts: sugar, phosphate, and a nitrogenous ... base pairs. There are two types of purine and three types of pyrimidine. The purines are ...

How can just four nitrogenous bases--adenine, cytosine ... could encode all 20 amino acids in RNA would be a triplet (three-base) code. A triplet combination, or codon, would allow for 64 possible ...