Now let's begin by let's move on to our nitrogenous base. So there are four different types of nitrogenous bases that are found in DNA. So we have guanine and anine which are the two types of purines and we also have the thymine as well as our cytosine. And the thymine and the cytosine are the two types of pyrimidines that exist in DNA. Now RNA nucleotides also contain adenine guanine as well as cytosine. However, thiamine is not found in RNA molecules.