We have a sugar, we have a phosphate group and we also have a nitrogenous base. Now let's begin by differentiating the type of sugar that exists in DNA and RNA molecules. So recall in DNA molecules the sugar that is involved is the deoxyribose sugar and the sugar looks something like this. Notice that on the deoxyribo sugar the second carbon does not have a hydroxyl group. However, the RNA molecules contain the ribose sugar and unlike the deoxyribose the ribosugar actually does contain the hydroxyl group found on the second carbon. So this is the ribosugar that is found on RNA molecules and that's exactly why our RNA stands for ribonucleic acid while DNA stands for deoxyribose nucleic acid.