This page describes nucleic acids in a simple but very thorough way. It talks about DNA and RNA. It talks about the pyrimidine bases: Cytosine and Thymine and it talks about the Purine bases: Adenine, Guanine, and Uracil. It talks about the the parts of nucleic acids and the parts of nucleotides. It talks about the structure of DNA being a double helix and how it is put together.