The backbone of a DNA molecule is made up of deoxyribose sugar and a phosphate group at the top. The inside of the molecule is where you can find your nitrogen bases: adenine, thymine, guanine and cytosine; however, the order of the backbone can be flipped depending on which prime is is located on. For example, for sugars (deoxyribose) that are located on 3’, the backbone is essentially flipped upside down. But for sugars located on the 5’ the phosphate group can be found above your sugar, AKA, right side up.