Now, on the tip of this phosphopancythine is a sulfide hydro group. And attached onto this sulfidel group is the next acetolico enzyme, a molecule that will be used to actually elongate that fatty acid chain. So we see that fatty acid synthesis incorporates carbon atoms from acetylco enzyme A molecules onto that growing fatty acid chain. And as we'll see in more detail, those acetyl Cozume molecules are attached onto this sulfidel group. Now, the process by which we actually form fatty acids isn't a very energetically, favorable process. In fact, we have to use ATP molecules to carboxylate, and then the process of decarboxylation releases energy, and that helps drive the fatty acid synthesis process forward.