So let's suppose we have the following sequence of nucleotides in a given RNA molecule. So this is the beginning, the five end and this is the end, the three end of the ribonucleic acid. Now, if we take this RNA molecule and place it into an aqueous environment found in our cell, it can fold into some type of three dimensional structure. And to demonstrate what a stem loop structure actually looks like, let's suppose it folds into the following structure. So this is the five and here and this is the three and here. Now, notice that this sequence C-U-G-A GGU, is complementary to the sequence gacucca.