RNA, just like DNA, stores information in four bases: A (adenine), U (uracil), C (cytosine), and G (guanine). Unlike DNA, the thymine bases are replaced by uracil.

The top is labelled 5 prime end. An orange circular phosphate is bound to the 5 prime carbon of a blue pentagon chemical structure with a grey base labelled U bound to the 1 prime carbon. Another phosphate is bound to the 3 prime carbon of the top pentagon as well as the 5 prime carbon of a lower blue pentagon. This lower pentagon has a grey G chemical structure bound to the 1 prime carbon. The phosphate bound to its 3 prime carbon is highlighted and labelled phosphodiester bond. This linking continues for two more blue pentagons.

RNA is copied from its complementary DNA strand by an enzyme called RNA polymerase. RNA synthesis proceeds in the 5' to 3' (five prime and three prime) direction. 5' and 3' refer to the position of carbon atoms in the sugar backbone. The 5' carbon has a phosphate group, and the 3' carbon has a hydroxyl group.

RNA is a very ancient molecule, with many different functions in the cell. Hence, there is a large variety of different RNAs.

RNA structure is very similar to DNA, however, there are some very important differences between RNA and DNA.