Uracil is a nitrogenous base found in all RNA but not present in DNA. There are multiple unusual modified bases found in tRNAs not found in DNA as well: Dihydrouridine, Pseudouridine, 1-methyl adenosine, N2,N2-dimethylguanosine, inosine, and 1-methyl-inosine. There are other nitrogenous bases that are metabolic intermediates that are not found in nucleic acids such as inosine (also in tarna), hypoxanthine, xanthine, dihydroorotate, orotate, and the purine break down product uric acid.
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