10. Differences between RNA and DNA Temporary molecule made only when needed Permanent molecule in nucleus Small soluble molecule Large insoluble molecule There is no fixed ratio between A and U, or between C and G Ratio of A:T and C:G is 1:1 Nitrogenous bases are Adenine, Uracil , Guanine, Cytosine Nitrogenous bases are Adenine, Thymine , Guanine, Cytosine Sugar unit = ribose Sugar unit = deoxyribose RNA DNA