Strung Out on Acid: the Formation of DNA and RNA

Let’s get a couple of nucleotides together. One of them has an especially long 5’ phosphate group, a triphosphate. This triphosphate group is just quivering with chemical energy, and that energy can be released when it’s hydrolyzed—meaning when it’s split by water or another hydroxyl-containing molecule. Heck, the triphosphate wants to be hydrolyzed. In this case, it’s attacked by the 3’ hydroxyl in the other nucleotide. We end up with biphosphate in solution, along with a brand new molecule composed of two nucleotide residues-—an oligonucleotide, essentially a very short nucleic acid.

 

Figure 5. Structure of Nucleic Acids. Nucleic acids are nucleotide polymers, in which the organic bases jut out from a sugar phosphate backbone like ribs. RNA tends to single strands, and DNA tends to be double-strands. There is a subtle error in the lower two panels--can you find it?