Both DNA and RNA are made up of threee basic parts: phosphate groups, sugars, and nitrogenous bases. The main difference between DNA and RNA is that the nitrogenous base thymine (in DNA) is replaced with uracil (in RNA). The other three bases remain the same, adenine, guanine and cytosine. In DNA, adenine always pairs with thymine, but in RNA, adenine pairs with uracil.
