© Left: Wikimedia Commons, Public Domain. Author: Narayanese, 27 December 2007. Right: Wikimedia Commons, Public Domain. Author: MirankerAD, 18 December 2009.
The chemical structure of RNA, like that of DNA, is relatively simple. On the left, we see a diagram of a portion of the RNA molecule that highlights its difference from DNA. RNA has a hydroxyl (OH) molecule—a molecule with one hyrogen and one oxygen atom—at the 2' position on the ribose sugar, where DNA has a hydrogen atom. The result of this seemingly innocuous swap is shown on the right: RNA folds into structures that are far more complex than the DNA double helix. (Unit: 9)