Nucleotide – a structural component of DNA and RNA. A DNA nucleotide contains deoxyribose and a nitrogen base of adenine, guanine, thymine, or cytosine, which form pairs called base pairs. An RNA nucleotide contains ribose and a nitrogen base of paired adenine, guanine, uracil, or cytosine. Each DNA or RNA molecule contains thousands of nucleotides. The order in which the nucleotides appear is the base sequence and conveys the GENETIC CODE for the proteins the DNA or RNA molecule encodes. Base sequences, arranged in triplets (trinucleotides), make up GENES.